Your Twitter feed is yours. It's like your home territory. People feel like they're entitled to defend this territory. Twitter assists inflammatory media as it attempts to invade this territory, originally with retweets, but more recently with algorithmically selected tweets coming from people who you didn't follow, selected for "engagement". But it does more than that. When you defend your territory, your defense ends up on someone else's feed as a provocation.
The original model worked, with tweets from your followers only, and no retweet support except copy and paste and the letters RT. The current model is cursed.
So like having hashtags in your profile, you could include ban-lists there, and your preferences would be calculated (and people could see what your filters were).
Yes, this wouldn't solve the issue of filter bubbles but the Twitter's algorithms could augment how to weight people's ban-lists with actual mentions/RTs - so I would see someone on only one of my ban-lists but got a lot of RTs/mentions I'd see it. If I find I'm not seeing stuff I should, I could alter my lists