This is not a tactic. This is a disability. Not being able to see what's going on is very bad. When I have a rook character teammate I find myself constantly spinning the camera around and it's very frustrating, because when he moves I need to spin the camera some more.
In the game I played on Exile the enemy were TB/Rook/Erebus/Queen and they were all bottlenecked at our base entrance with Giants and other grunts. I try to hover with the mouse but I could not pinpoint exactly who is where. I had to guess (except for Rook, of course). Finding Erebus in the crowd was a fricking joke. Same goes for the TB.
This doesn't happen every game. But on certain bottlenecked maps (Cataract, Crucible, Exile) it becomes very problematic.