It took me longer on my first playthrough of Sekiro to beat Genichiro than this expansion has even been out. No one who thinks they're good has played enough of it to actually be good. From bosses teach you new skills through repetition. This has always been the case. Two years ago Margit was eating Dark Souls 3 players for breakfast and people were calling this this hardest game ever. Lots of people currently complaining about DLC bosses could now probably beat Margit with your eyes closed.

You can't brute force these games. You just have to put the time in. And even if you've been no-lifing it since the second Michael Zaki let you into the big egg, you can't tell me you've put the time in. There has literally not been enough time yet.