They already do that in NYC. It doesn’t help because the following stops are full of extra passengers and the crowds on the buses quickly equalize while they remain bunched.
I didn't state it that clear, but I am well aware that adding overtaking to the equation doesn't solve the bunching problem .
But the bunching itself is not a problem. The problems are the effects it causes like:
1. crowded busses
2. arrival delays
Overtanking has a major impact on the first effect as you have stated too, the 'crowds on the buses quickly equalize'. The impact on the second effect depends on some other parameters. If all busses are crowded there will be no effect at all, but if only a few busses are crowded (the front busses) and the busses behind them are empty, there can be a positive effect on the arrival delays too (the worst case drop off time will be lower).
So I would not say 'it does not help' as it certainly decreases the negative effects.
But the bunching itself is not a problem. The problems are the effects it causes like:
1. crowded busses
2. arrival delays
Overtanking has a major impact on the first effect as you have stated too, the 'crowds on the buses quickly equalize'. The impact on the second effect depends on some other parameters. If all busses are crowded there will be no effect at all, but if only a few busses are crowded (the front busses) and the busses behind them are empty, there can be a positive effect on the arrival delays too (the worst case drop off time will be lower).
So I would not say 'it does not help' as it certainly decreases the negative effects.