Yeah, I think it is a consequence of the nature of federation like you said (not saying federation is bad, of course)

At Reddit, everyone had to coexist and conform to the overarching group of admins and site-wide policies, whereas anyone on Lemmy, should they find the admins of an instance too restrictive, can just make a new instance that allows for whatever extreme they desire.

Thankfully, a lot of the major instances like lemmy.world seem to be closer to the middle- still biased one way or another, but not nearly to the extremes of Lemmygrad or Exploding Heads