Read my other reply, I'm not talking about email blocklists, my reference is to email providers doing that, which is extremely rare and done with explicit intent and good reason.

Secondly, while I won't disagree there's some vile content out there on the Fediverse, do you trust someone else to make that decision for you? Why would you let someone else decide what is and isn't vile for you and those using your instance? Better yet, how would you feel if some popular instance decides you were the vile one, and because it was a common instance to use for blocking references, your instance is now cut off from a good chunk of the Fediverse?

This is exactly the sort of nonsense that swept Twitter with shared Blocklists, and the potential for negative impact on the Fediverse is even worse from it. Don't let others decide make decisions for you just because it's easy, as it doesn't absolve you of responsibility when something goes wrong.