Reduces the chanes? What,.even blocking is RNG oriented? I definitely think that a player should be able to throw only some players out of his experience without needing to resort to solo or a limit himself to a group.
It's not RNG, think about the scenario above.
You say "a player should be able to throw only some players out of his experience without needing to resort to solo or a limit himself to a group", but you don't own the instance it's a shared space.
Like think about you're in a pub, but you have a blocklist saying you don't want to see Dave cos he's a . Well Dave's mate walks in, all is well, no problem. But two hours later well here comes Dave, what happens???
Dave wants to be with his mate, his mate is waiting for Dave to arrive, but you don't like Dave. It becomes a conflict that has to be resolved somehow.
If Dave was on his own then it wouldn't matter, the system could stick him in another pub, but he has friends that are not in your blocklist already there.
You simply do not have rights to control the pub (instance) it is shared.
To be honest I think the only real solution to this would be something like, your nemesis Dave walks in, so you get a pop up asking you if you want to leave the pub and go to another one.
But you can then see that just turns into a feature that can be abused to track players you want to grief.