It depends. Defederation for good reasons is good, defederation for bad or false reasons is generally bad.

As an example, having a strict and democratic defederation/federation policy has contributed to Hexbear having the most active trans community on Lemmy, and it's a good thing that there's an actively protected trans space free from bigotry.

At the same time, defederating from instances for political reasons under the guise of other reasons is generally a bad thing.

It's largely context dependent.

Well that's definitely your own experience on federated platforms, but I wasn't speaking to that circumstance. I made a mastodon account and criticized our government's massive funding of Israel in spite of our lack of critical infrastructure and healthcare and got spammed with "Israel has a right to defend itself, and you 're a trumper if you think otherwise" type comments by people that post one response and then immediately block you. Which is laughable and couldn't be further from the truth. That is the perpetual echo chamber I was referring to from my personal experience.

Are positive, liberal LGBT communities echo chambers

Could be, especially if there aren't a multitude of sentiments there. That doesn't mean all sentiments must be present of course.

Are they not allowed a collective space to hang out without having to explain themselves all the time

I don't think anyone said they aren't allowed to have such a space.

You're in an echo chamber if you curate your home feed to only show one opinion and then never change it; it doesn't matter what the opinion is

I’ll take this comment more seriously when literal nazis stop demanding we listen to them.

There's moderation and there's making it into an echo chamber. Seems like a difference many don't understand.

Hope you get the help you need 🙏

You're talking about Exploding Heads, which has been defederated by pretty much everybody.