I think part of it is that leftists (myself included) don't like being lumped in with tankies. I didn't downvote though.
The lead devs of lemmy are tankies, basically meaning authoritarian communists of the genocide-apologist variety. They also run the lemmy.ml and lemmygrad.ml instances.
This is also why I signed up on kbin instead of on lemmy. The other lemmy instances are fine, but I don't want to contribute to the influence of the lemmy devs any more than necessary. Hopefully they try to pull something stupid and get forked off the project.