An instance can block federation with another instance (an instance admin must do this on the instance server), but for you as a user of an instance, you cannot block the whole server. What I did is exactly what you describe. This way, I have only the content I am interested in my post feed. It takes a while, but it serves the purpose.
An instance can block federation with another instance (an instance admin must do this on the instance server), but for you as a user of an instance, you cannot block the whole server. What I did is exactly what you describe. This way, I have only the content I am interested in my post feed. It takes a while, but it serves the purpose.