more parity than the sport of football allows.

In college basketball, two star players could join forces and go to an average/nobody school and make that school a contender for a few years. In football, we need like 15 to 20 stars working together to go boost some surprise school.

A few schools can still easily hoard the 5 star recruits even with an expanded playoff.

I would say that NIL is a more likely tool to increase parity than expanded playoff would be. If an outsider school can put the funds together for the players, then they could get a large group of top recruits to come play for and boost their school for a few years.