> We see other flights to our destination that were scheduled after ours from the same airline on the same type of plane boarding and leaving.

I feel like there is a lot more to the fungibility of planes. E.g. add just one more consideration, like bag loading, to the scenario and suddenly you end up with a mess of not great answers for a whole complex tree of things unless you somehow know with certainty how long the fix is actually going to take ahead of time. The more of these additional considerations you add, the more they start interacting with each other and the less likely "just switch the planes" only means passing the delay along.