@zeroase A few reasons.
First off, I actually don't have an issue with my current instance, for the post part. My interactions with most people on this instance have been decent. The problem is that the Fediverse, as a whole, is full of people just waiting to attack people like me if we decide to ever discuss anything in the political side of things.
The original post that started that whole thread was one by Eugen Rochko, he was encouraging people to leave positive reviews for the official app on the Play Store because there were quite a few negative reviews saying Mastodon is a left-wing echo chamber.
My first reply was that they weren't entirely wrong: even after strenuous blocking, word filter lists and even straight-up instance blocks, I still see all sorts of left-wing political stuff in the Explore feed. It's literally unavoidable. I joined this instance, and the Fediverse as a whole, to connect with people in the IT space and chat about stuff we care about, but over the past few months, I see loads of political crap again. It's especially horrid since the election.
The fact that I had two of my posts removed for a mutually civil discussion (which seems all too rare for political discussions here) is problematic. Even if I move instances, I'll still encounter loads of these sorts of ridiculous posts. Plus, like I said, I did enjoy using this instance due to the fact that a lot of people here are into the same sort of stuff within IT that I am.
Oh, and the 11k character limit is especially nice to have for people like me who tend to be very verbose.