Are people pretending to not see a real problem in the PVP arena?

You're looking at the wrong thing though. It's not an issue with the game. It's an issue with outside communication. If people couldn't communicate outside of the game, the only way this could happen is if the people from the same arena shard were in a guild together. In that case you could blame the game because of how allies are suggested. Otherwise it's a product of outside communication, not from the game itself.