I really did always hate that Reddit felt like a massive echo chamber.
Lemmy is a collection of independent echo chambers that believe different things. You can make an account on some instance you never heard of before and get people assuming you have certain beliefs just because of your instance because apparently a lot of people stick primary to their home instance? In one instance, you have an echo chamber of "bOtH SiDeS aRe tHe sAmE" and other echo chambers that say things like "I won't vote for someone who aids in genocide".
Some instances block more instances than others (the one you are on has blocked 172 instances, for example). And some instances are blocked by a lot of instances (lemmygrad is blocked by 89 instances). Also some instances disable downvoting, if that's something you're interested in.
I don't think overpolicing is an issue in most places? Like, there's that one person who openly is pro-genocide in all of the palestine-related threads (like, they explicitly call for killing of even infants and that anything less is antisemitism) and I guess they're tolerated (just probably one of the most heavily downvoted people on lemmy). But if they're on an instance without downvotes, they wouldn't even see them.