https://news.ycombinator.com/item?id=28495086
http://ceur-ws.org/Vol-2737/FP_6.pdf
There was a huge uproar about it a couple of years back.
EDIT:
https://www.reddit.com/r/Mastodon/comments/jkiw1y/can_someon...
Gab was "banned" in that the vast majority of instances blocked it and blocked any other instance that didn't do the same.
If that's not censorship, I don't know what is. You can have your sandbox but you can't play with others unless you accept their censorship rules and politics.
No, that doesn't make it make more sense. You're saying Pleroma instances cannot decide to de-federate with a specific instance, and can't remove/moderate posts? That seems... unlikely.