I'm reading the reactions to the SPN finale and having total flashbacks to HP. Usually I don't think of those canons being very similar, but they both have characters with strong personalities that color all their reactions. They can get hurt by someone saying something not intended to hurt them, or do something that's hurtful to someone else without thinking it's hurtful. They can do obviously the wrong thing while thinking it's totally the right thing.
It makes the interactions fun to analyze to tease out how the characters are talking past each other or influencing each other in ways they can't understand, and makes every character an island where they can't ever truly understand the other person. I mean, they can understand them based on familiarity with their behavior, but if you asked them to analyze the other person it would probably bear no resemblance to how that character saw themselves.
But this leads to a fandom with a lot of different factions who see one character as right or sympathetic and other characters as wrong. And along with that go assumptions that if you disagree with someone on which character deserves understanding it must be because you're a stan of that character and so completely biased, rather than just seeing a grey area a little differently than the other person. The show serves up a sad, tragic situation that mixes love and resentment or has characters having a bad influence on each other without meaning to, it is guaranteed to cause fury!
Not generalizing the whole fandom with that there. There's plenty of people not doing that and writing about it, I've seen it. I'm just totally not surprised that after that finale there's a lot of fury going on, with different groups complaining that their character was dissed and hated on by the writers and will continue to be so while other characters unfairly elevated. The messiest fictional situations inspire the loudest insistance that it's all very clean and simple.