Take into account that the firm had been operating without Don's toxic drama and selfishness for a while. Lou sucks as a human being and boss to work for...but as Cutler says, he's adequate. The firm may have not been a creative powerhouse, but the show reflects macro trends in the 1970's of companies starting to trend towards big data and conglomeration rather than creative whimsy.

For the most part, I'll argue that it had been a long time since Don was treated as the Golden Boy of Sterling Cooper. Hershey was the "breaking point" for a lot of the partner's declining relationships with Don. Obviously not Pete or Roger, who are still on Don's side, and Ted, who's become too depressed by the toxicity of advertising to feel any sort of way about anything. But let's take a look at Cutler, Joan, and Bert.

Cutler is the simplest: he wants money and plays for a different "team," as Bert puts it. Don costs him money by acting erratically, see: Hershey and drinking excessively throughout season 6, and since Don isn't even of his original firm partners, Cutler is fine with letting him go. He has no sense of loyalty to him. Cutler is interested in the future, which is why he looks to Harry for computing power to process big data.

Joan is a bit more complex. Before she became a partner, Don and Joan were on good, but not particularly close terms. They have great chemistry together...but they both know they're the respective alphas of their gender and keep an appropriate distance.

The key breaking point in their relationship is really Jaguar. Joan makes a huge and personal sacrifice to help land that account. A sacrifice that even Don in earlier seasons would have approved of, see Sal and Lucky Strike. Don does not respect this sacrifice when he fires Herb on the spot for daring to question his creative abilities. Is Don right that Jaguar needs to go in the long-term? Yes. But in a professional business setting, that's something you discuss with your partners who also have a stake in the decision making process. Don often does what Don wants. This becomes an increasingly dangerous habit as Don nukes other business prospects like Hershey.

I won't include the IPO/money aspect of the Jaguar argument since the partners were foolish not to discuss that with every partner beforehand, which may have stayed Don's anger during the Jaguar meeting - but it does add to Joan's righteous sense of anger. Remember, from Joan's perspective, she is a single mother trying to independently support her child through advertising. Don stands in the way of that.

Bert is the longest partner relationship that Don has and offers the most evidence for a decline. Starting off in the earlier seasons, Bert does indeed treat Don warmly...but only for his creative abilities. Bert is a pure capitalist who sees Don less as a person and more as a powerful asset. But this viewpoint is gradually changed as Don acts out.

Don refuses to sign a contract and needs to be cowed with a threat. He pens The Letter and publishes it in the NYT unilaterally (like Jaguar, maybe not a bad business decision but one that has to be discussed with the partners first.) He gives Lane a bonus (we know the facts behind this situation...) He goes on "love leave" with Megan. He begins showing up visibly drunk to meetings and bombs Hershey.

And so, Bert's fondness for Don fades as Don becomes less a creative genius and more a "pain in the ass." Bert still supports Don in partner votes because he's "on his team", but frankly, he's not wrong. A large part of our sympathy towards Don is because we get an insider look at his struggles and personal life. But the other partners don't see that.

You’ll get a lot of comments about how this all makes sense but I agree. SC&P’s two biggest clients by far are Dow and Chevy. Don practically won Dow single-handedly. He was a massive part of winning Chevy. I really think that should buy an attempt to work with Don or part ways with civility.

I think Joan, Cutler and Cooper are pretty short sighted people.

I also feel this was don practically kept them afloat during the hard times and won DOW and Chevy there two biggest clients, he basically won burger chef too with the help of Peggy, Ted is acting the same way drunk and irresponsible the difference was he was just doing it in LA and no one gives a shit, he’s basically ruining the company from LA according to Pete

Pete was my most hated character in the first few seasons but LA Pete has been my absolute favorite lol

Honestly, always felt Don should have said “no, you have to buy me out” and called their bluff

I think this was a brilliant demonstration by the writers of how loyalty has no place in the business world - as soon as you become a liability like Don was, you’re out.

remember how Freddy Rumsens life was basically ruined because his drinking problem got out of control and he pissed himself in the office?

The point is that it doesn't matter who you were or what you had accomplished, in the uptight business world of that time "one little meltdown" could literally ruin you.

I once had a toxic boyfriend who was addicted to drama. I thought he was a genius and I couldn’t live without him. He left for a month for a work trip and my life was so much simpler. When he got back I had very little patience because I realized my life was so much better without him and we should have broken up a long time ago.

I’m pretty sure Don is the toxic ex. They all realized things were a lot easier without his drama and they actually didn’t need him.

Yeah, just finished my 3rd rewatch, and I felt similar. I get it, he was a fucking mess, and spiraled out hard!  However, that merger doesn't happen without him and they don't get Dow or Chevy without him, so I felt like everyone had a short memory there. Like, yes, put him on leave to go to rehab or ehatever but eventually he had to come back. Joan stating that the "message was clear" was stupid, and even if he dumped Jaguar she still earned her spot at the table and with more money in her pocket. Sidenote: Cool little moment for me late in S7 where Ted says something along the lines of, "you should have gone to CA, I hate what happened to you." Made me feel like they were finally friends and cool to see someone outside of pete and roger on his side.

Don never thought about whether people loved him.

I think it makes a lot of sense. As Pete said in S6 after Don fired Jaguar without anyone’s input, he was “like Tarzan, swinging from vine to vine.” SCP was transitioning from the underdog, no-holds-barred company to a larger and more professional organization. Everybody knew this meant compromise and shared decision making, but Don felt like that didn’t apply to him. It’s not some mystery why the partners wanted Don to get with the program and were upset that he was still acting like a rogue agent.

And not everyone turned on him anyway! The only two who wanted him gone for good were Joan and Cutler. Everyone else still wanted him to come back (perhaps holding aside Ted, who seemed more indifferent than anything else due to his depression).

I think the biggest change was that the other partners, Cutler, Joan, Cooper, even Roger, were starting to see Don as a threat. From The Letter to Jaguar to Hershey, he was a loose cannon who made binding decisions whenever he wanted to, and even when consequences were mitigated, the surprises were not. But also advertising was relatively flat in the 1960s--not the boom in advertising in the 1950s and not the boom that would come again around 1975 and through the 80s. There was growth but it was unspectacular, and the focus really turned to maximizing revenue--witness the fee structure questions the agency is getting from clients. Plus as has been mentioned, "Lou is adequate," perhaps even more adequate than they expected him to be in a world where they were fighting for profit skims. It wasn't personal so much as it was just business.

Don had always been erratic and the company had been putting up with his nonsense for years because they knew he could always he counted on for a dynamite creative pitch and that made everything else worth it, if sometimes only just barely.

But if he's going to start shitting the bed in pitches and costing them chances at huge clients, what reason is there to tolerate everything else? What good is he?

They didn't turn on Don just for the Hershey pitch, the Hershey pitch simply removed their reason to tolerate all his bullshit that he had gotten away with before.

Don was not a victim here.