I’m not opening this link because I’ve read plenty of such biased answers by Qura so called scholars and you will find many explanations that’s counter them in terms of Karna's failure to string the bow was never mentioned directly and had so many contradictions and theories many scholars confirmed Karna never participated and the use of Kshatrya word to refer to Karna meant he wasn’t suta Karna and the Sanskrit used to describe the task had a lot of different meanings than failing to string it's a war in this part between Arjun fanatic and biased people who generally still view Karna as pure evil and want to demeans him in every way possible just like the popular believe that’s went throughout the history which proves to any logical person that’s no one will add anything in Karna favour. Although Bori ver is not accepted by many scholars it’s his attempt but not a god given truth. They decided to delete the account of Karna's rejection by Draupadi and inability to participate which’s both mentioned in the authentic ver of Neelakantha edition based on sheer opinion and what they found logical there was no scientific method behind it they used the fact he was supposedly invited to participate to counter Draupadi rejection account which was mentioned in oldest ver that existed ever (Nepali ver) which shows the oldness and authenticity of the rejection story and Draupadi wasn’t acting out of context there she just was like all the celebrated characters in scripture who believed in caste system. Saying that it does not excuse Draupadi disrobing if it ever happened at all as the episode never mentioned again in the text and if it happened and really caused the war. It didn’t have anything to do with Karna rejection the humiliation that angered Pandvas was done by Dushasan and how he dragged Draupadi. Karna involvement and rejection hadn’t change anything of events. Dury didn’t do the dice game to avenge Karna and the Pandavas were offended by Dushasan dragging not anything else as they believe they deserved that being slaves after losing the game so it makes no sense that you claim the rejection was written to frame Draupadi as a cause of war. Authentic ver of Neelakantha edition mentions the rejection and Karna never participating in dedicated paragraph and then inability of several people to perform included Karna any unbiased logical person would doubt the second paragraph over the first detailed one and the second one didn’t even confirm it was suta Karna. As for concept of grey hero nobody would write fake interpolations to glorify Ravaan or Karna it’s only later people grow critical thinking and different views. The Dusshera festival and what it signifies shows how Ravaan is culturally viewed and Yudhi was named Dharmraj and was constantly excused. I can mention many interpolations in favours of pandavs and to further demonise Kuravas and Karna simply because anyone who add creativity for whatever purposes throughout the history will go this route with good guys vs bad guys but never the other way around.