Blocking instances actually makes the lives of instance admins a lot easier. It not only reduces a whole chunk of problematic content for you to moderate, but it also encourages Nazis to go to the servers you block instead of yours. Nazis can't subscribe to the subs they want to on your server, and they get banned if they say Nazi shit, so they just leave and go to a Nazi server instead. It's like fly paper for Nazis lol.

As a Mastodon admin with a few thousand users, I rarely see Nazi content that I have to moderate. And that's because when I started I spent an enormous amount of time sifting through every server we federated with and blocking all of the Nazis and all the pedos and all the TERFs. And because I did that at the start, I only get maybe 10 reports a week, none of them are content that would traumatize me (almost always spam), and I also helped the servers that now use my list to do the same.

Blocking instances not only makes it easier for me to do my job, it encourages other admins to not tolerate these kinds of behaviors as well. Because if they don't moderate well, that attracts Nazis, and then we have to limit or ban them because we're volunteers. So everyone just ends up blocking the shittiest servers and moderates their user base well. It's a win/win for everyone.

Nazis are not entitled to access to minorities on my server. TERFs are not entitled to access to trans users on my server. Assholes are not entitled to have access to an audience on my server. There are tons of white supremacists or TERFs or other assholes hosting plenty of other servers where they can go and do that. But I don't want that on servers I host and my users don't want that on servers I host. If you truly believe free speech is such a big fucking deal, then you are welcome to leave and join one of those rotting servers as well. See how fun that is for you and how long it takes for you to come crawling back.