SOME of that sentiment, at least in the past week or so, is coming from the finding that poorly managed AP servers are vulnerable to abuse and create problems for the broader network.
Mastodon is scrambling to mitigate some of that. but there are a lot of “friends and family” servers out there that need more support than just Dad or Aunt Liz are able to put in.
Unfortunately most folks are not careful enough in expressing their reasoned objections and just seem hostile.