Just a quick note that PieFed allows you to block all users from a given instance, like a personal defederation with no need for admin powers. Your way also works, but you’d have to block thousands of users individually, plus new ones that sign up later.

While in contrast the option that looks like it would work easily, the “instance block”, in fact is strongly misleading - still allowing those users to vote on your content, reply to you, submit posts in other communities, DM you, triggering notifications, etc. Essentially it does not “block” the “instance” at all, only muting communities hosted on them.