Twitter / X, for political reasons, allowed extremely toxic behavior while at the same time disempowered communities from moderating themselves. If you force each individual user to manually block every troll, bot, or disgusting person it's a losing battle and low quality speech will overwhelm conversations. X folks know that but did it anyways.
It's also becoming more and more clear that we need a relatively neutral medium for free speech. Musk claimed to be building that on X but then did exactly the opposite. It's very hard to trust the algorithm isn't being manipulated in one way or another.
On BlueSky it's incredible how much value is already being produced by connecting intelligent and creative folks as compared to what Twitter became.