Lemmy is a relatively small and niche platform, imo small platforms tend to be like that. First men show up, then transfems, and then cis women. We seem to be at the second stage and while things can be done better (like a female only instance) I do think things will get better.

In Mastodon, this is typically solved with defederation, block lists, and admins enforcing mod policies. How come this approach doesn't work for Lemmy? Is it not decentralized enough?

I would moderate it :(

Tbf, i wouldn't recommend Lemmy to anyone i know either for more reasons including this

I had much more toxic behavior at reddit, but it is hard to imagine any safe space online anywhere.

I think it's much better then literally anywhere else on the internet. That doesn't mean it doesn't happen, but unfortunately everywhere else is worse. As such, I'm not sure whaz the solution is for Lemmy in particular.

Everywhere where it seems "better" is just moderation making it seem like that.

And this I why I don't either