Ah this is an interesting idea. Passengers already have to request when they want to get off. I'm assuming you mean if no one wants to get off, a bunched up bus skips a stop because a bus behind it says "I'm behind you, I'll take this stop."

That would mostly work, but the problem in Pittsburgh at least is the bus bunching happens between related but not quite identical routes. For example, the 61A, 61B, 61C, and 61D all run down Forbes Ave, and frequently get bunched there. But then later in their routes, they fork: two go one direction, and two go the other direction. For many passengers, it doesn't matter which one they take. But for other passengers, it has to be a 61A etc.