Cav was op as fuck. A half decent cavguy could easily get a score of 10-1 with a rouncey.
And one good archer can easily defeat anywhere from one to a handful of cavalry on his own. Add in a pike and you might as well just not use the horse in the first place.
Cavalry has a place as the hammer in that old and useful tactic, but that does not make it overpowered. Especially not in a random battle or siege where everyone and their mother kills horses like it gave you a trophy and free ice-cream.