I show up for a flight to Mordor scheduled departure at 8 am, you for a scheduled departure at 9:30 am.

The plane scheduled for the 8 am departure is unavailable (for whatever reason) and there's a plane that can board for a 9:30 departure... Shouldn't I get preference since my flight was scheduled to leave earlier? When the other plane becomes available or is replaced, your flight will go out on that (or whatever flight in the swapsies chain).

What alternative would you prefer:

a) Early flight has to wait, maximal delay for those passengers trading off with minimal delay for others

b) Something based on class of booking + airline status + time of booking, like they use for upgrades. Frequent fliers get minimal delay, ultra economy gets maximum delay

c) prefer passengers with connections that haven't yet been missed, otherwise a or b? Maybe just prefer passengers where makable connections avoid an overnight missed connection. This one makes systemic sense, but may not be easy to compute.