Why have a coach?

I watched a video of a bizarre game from 1974 between Tulsa and Oral Roberts. If the venue had been a local playground instead of a college arena, it would have fit right in. No offensive scheme. No defense to speak of. Tons of turnovers. It literally looked like what you would expect to see in a pickup game on an outdoor court.

That brings up the question, What role were the coaches filling? They were sending in subs. They had recruited the players. But as far as bringing any structure to the game, they might as well have been in the locker room. It was weird.