Wrong comparison. It’s not like a server admin using an email block lists (which are also often implemented badly, as anyone with a protonmail account knows…). It’s more like if Protonmail suddenly blocked Tutanota, or if Gmail blocked MS Exchange. The uproar and rage from that would be unceasing.
The Fediverse operates on a model like that of email, and in the email world blocking whole email servers from each other is very rare, and usually done with the most explicit of intent and for a very good reason. That’s how the Fediverse should operate as well.