Earlier quoted context omitted.
Twitter is only like that if one consumes that content. Like, if one only ever follows John Carmack and Gwern, that won't be the experience. Saying Twitter is mean-spirited is essentially the same as saying that no matter where one goes one smells shit. Everyone who feels that way should check the bottom of their shoe. I suggest Matthew 7:5 for them.
It's just too much work pruning / hoping you find folks who are sort a single topic accounts for me. Often they fall off the wagon and get into spats and so on. Too much hassle to constantly add / remove folks to keep a feed that isn't "typical social media feed BS".
The main cost is that this isn't conducive to a very large following list, but perhaps that's a good thing.