I think there’s plenty of diversity. However there is a tendency on certain instances to completely dogpile anyone who has the Wrong Opinion on certain issues, with extreme hyperbole.
Take the AI thread going on. People keep referring to environmental costs as if using an AI query is the equivalent of burning down a whole tree. You consume way more energy just charging your phone. Watching a video. Playing games. Yet using an AI is bad enough to get you called a fascist, an eugenicist and other fun things. The lack of perspective is staggering but certain section of Lemmy users have just decided that AI is evil and any nuance is wrongthink. Even just accepting the reality that AI isn’t going to go away is seen as evil comparable to murder.
Other example is the db0 blocking feddit.org debacle.
Yeah it course corrected a little bit but it did not start out very well. The brainless, misrepresented link dump is the highest voted one. As people pointed out, link dumps like that are straight from alt right playbook. The one reply that called out the issues got removed by mods and it was heavily downvoted initially (actually the timing and amount of upvotes and downvotes in those two comments, and how it evened out makes me think someone was vote manipulating when the link dump was posted). One of the comments from the link dump user was calling the debunker an eugenicist too and that got way too many upvotes off the bat than makes sense to me.
Like I said, there’s diversity of opinion but some users, instances have pretty terminally online, black and white opinions that lead to downvote burials. And for a lot of people, that does signal “this is what I should think/this is what I shouldn’t think”. If it’s not the case for you personally, cool. But black and white thinking is so much easier and upvotes/downvotes play right into that.