I have been on reddit for just about 12 years now. Something I've noticed over time is just how hateful the place has become. A complete outrage machine. Every single sub became filled with it. I've filtered so many subreddits over the last few years, it's insane. I don't know enough about this place to be sure, but I do hope it doesn't become the same type of echo chamber of anger.
It's about 10 years ago they slowly began to forget their own reddiquette rules, 5 years ago they had almost vanished completely, although you can still find the rules on reddit, nobody upholds them anymore.
Lemmy is a more fragmented system than reddit, but so far the lemmy instances/servers I have seen have pretty good rules, with few exceptions, that have been defederated.
If lemmy gets really big, I'm guessing it will split into spheres of different rules. For now I'm happy with the rules of lemmy.world, let's just hope there will be good mods enough to uphold them.
I don't consider sociopaths as norms. I think reddit turned a bit infantile along the way, children testing boundaries or trying to be edgy can be a huge nuisance.
No matter whether it's "norms" or other groups, the only force that can hold a community civil long term, is good moderation. Without it any community is most likely to devolve.
That requires volunteers who care about the community. I think most people here are helping by not being asshats.