Oh Lordy you really don’t understand calculus at all
There are applications galore including economics , physics, chemistry, nuclear, and si much more. It is the study of rage change. Without it you will not be able to do any of the advanced math that is required for real science and engineering
Rate change!
Though you could model “rage change” as a rate, say the “change in rage per fortnight” .... That would be a medieval rage change!
Rate of change not range of change?