Open isn't cohesive. Somehow I think you have the wrong mental picture of it. In Open, you don't see all the other players at a location, just a selected group of them. In AX play it's not unknown to relog after a coloured-snake error and meet an entirely different group of people with the Thargoid encounter at a different stage. Using Block to avoid one group and get into another doesn't really have much effect on anyone's instancing.
This is a familiar impasse. Some want me to refrain from using Block. I reply that I use all game features to get the play I want in the game I bought. I'm not responsible for FD's coding.
What I dislike and oppose is that blocking can be ahead of time, and that its arbitrary. Its why I say it breaks things like Powerplay because groups can essentially block out other groups without ever seeing them which diminishes Open as a mode. It also inhibits gameplay for both because rather than use whats in game to overcome one party just removes the other for no penalty.
As for the wider game (such as AX) I have no issue with block because it does not have a player driven opposition.