I imagine it would be hard to expect players, most of whom have not undergone extensive training and practice, to maintain any form of tactical alignment, especially in a video game played in real time. I have not played any type of online "cooperative" game, but I would think breakdowns would be quite common. I see it in tabletop RPG games in which, once combat occurs, players play their respective characters as if in isolation with very little cooperative tactical maximization occurring, and they are sitting next to each other physically.