I accept that I overlooked your distinction here. You are right that there's no recursive blocking with email.

But I also think that's an oversimplification, because the block list is a helpful proxy for content characteristic of an instance.

But this is a case where I think the analogy to email breaks down insofar as its instructive to social media generally, because some things about email don't cleanly map on to what federated instances are managing. It makes sense that you would want to block instances and their enablers, to connect to an ecosystem consistent with the intentions of a particular instance.

As parent commenter said you can use a general purpose provider (with email) or general purpose instance (with Mastodon), so you are accessing the fediverse. The only thing you are "missing out" on is the ability to make it compulsory for other users to listen to you against their consent.