I'm with you - I was on Voat back when it was still Whoaverse. I bailed pretty early once I saw the direction it was heading in.
That said - the nice thing about the Fediverse is that there are multiple communities, with different moderation styles. Lemmy has a sizable communist community, for example, but you don't have to associate with them. In fact, some of the larger Lemmy instances (like Beehaw) don't even federate with them; you have to go out of your way to subscribe to them if your home instance is Beehaw.
So if what you're saying comes to pass, and the Alt-Right comes to Lemmy (I don't think they will, but let's imagine) - you can easily pack up shop and migrate to another Lemmy instance that has a better moderation style, or one that won't federate with those instances. It's just like Mastodon in that respect.
@nachtigall @WorriedGnome In addition to the above - you can also post from Mastodon!
It is currently one-way: Mastodon users can follow Lemmy communities and interact with posts; you can't follow Mastodon users from Lemmy.
But it's super neat that it's able to do that at all! For example, I am replying to you from my Mastodon account. If you hit the little "Fediverse" link next to my name, you'll be taken to my profile on my Mastodon instance.
This is because both Lemmy and Mastodon are part of the Fediverse, and thus can understand the data they send to one another. So to me, your stuff shows up as toots in my timeline... and to you, this is a post on Lemmy!