CX manage perfectly well with four queues: F/DM/Emerald, J/GO/Sapphire, Y+/Silver/Green/Ruby, and Y.
AA manage pretty well with up to 9 boarding groups. Even with a crowded boarding area, I have always been able to get through with a Zone 1 boarding pass.
This stuff is not beyond the wit of man, but it relies on a company recognizing the value in it.