Blocking can't possibly stop them from seeing your posts... they may not even be on the same instance as you, so rules on your instance don't do anything to them. And if it did, all they'd have to do is log into another free account.
Blocking is an "I am ignoring you" feature not, not an "I'm hiding from you" feature.
That said, I wish the Notifications tab even worked... I just get Error 50x every time I try to open it, which sucks because the counter is showing a notification and I can't find the message it's on to clear the counter.
I have also... but those sites weren't federated were they?
The fediverse is not "a site"... it's a network of many independent sites. You can do whatever you want on your instance, but you don't get to control all the other instances.
If you demand the ability to mute other people and prevent them from communicating with each other, you are fundamentally in the wrong place. If you choose to make a public statement, the public gets to respond to it. Your choice is whether or not you want to read their response.