The neat part about the fediverse is that no matter how badly behaved a dev may be, there'll be enough people to fix their behaviour and work around it. Look at mastodon, gorgon made a few questionable choices but glitch and all the other forks work around it and enough community servers exist that you could block mastodon.social and never miss a thing.
Just like with Lemmy there's already kbin and countless other alternatives that all integrate with each other and enough community servers.
But with browsers that's stopped being a thing a long time ago as the modern web is far too complex for small groups of indie devs to make their own browsers.
Often enough, the old code is so badly intertwined that it's impossible to actually test. Those are the moments where all you can do is nuke it from orbit.