Well reddit unpopularopinions is just popularopinions or some milquetoast critique of some piece of media, but lemmy most people aren't trying to be edgy or get upvotes.

Sometimes it's some nonsense but I've seen a couple good ones, ex: don't "just let people enjoy things," some pieces of media make people think less critically and is generally just bad for their brain, even if it's a fun thing for them. That one is like yeah I almost didn't want to read that because I don't want to have that extra layer I have to think about now, but it's important to keep in mind.