Honestly? And I promise I'm not being sarcastic: Reddit and Twitter are still your home. But the same goes for centre-left liberals. It's not that you're conservative, it's that you're moderate.
Many of the recent arrivals to the fediverse (myself included) are here because we're fleeing the corporate internet. We feel strongly enough about it that we've thrown all our toys out of the pram, abandoning huge platforms to try build this new space. This kind of behaviour isn't exactly "centrist".
So this nascent lemmyverse has a wiiiiide breadth of political views but not as much in the middle because those folks are all still on the old platforms. Over here we have Nazis, hexbear and shitposts. And porn. It's still early days.
Yeah it's a pity - I hope the core Lemmy devs can find a way to facilitate personalised instance blocking, but I have a feeling that it's not as simple as it sounds.
Edit: I had a closer check and I don't think the Lemmy protocol itself currently allows you as a user to block an entire instance? Someone smarter than me please correct me if I'm wrong.
I don't know the full story but I'm aware of an association between pleroma and some of the nastier, nazier corners of the fedi. My guess is that many of the larger instances running pleroma have been defederated from their masto counterparts.
If lemmy.ml is accepting signups I heartily recommend it.