I wouldn’t say defederation is rampant, but there were a few very high profile examples that hit right when people were new. Specifically, Beehaw/LW and Exploding Heads/everyone. Plus the whole thing about NSFW content and types.
While it’s true that many of the original devs have problematic views, it’s not really meaningful. The software is open source, there are tons of new developers (with varying views), and the code has nothing to perpetuate their ideas. In fact, they are pretty isolated on their own instance (Lemmygrad) since everyone defederates them almost immediately.