I wouldn’t say that, but reality shows that cav UUs aren’t adding a lot to a civ in most cases.
The knigh line is just too strong and easy accessable and cav UUs lack exactly in this department.
I mean we have a bunch of really op cav UUs actually, but they are hardly played:
konnik
keshik
leitis
coustilier
boyar
…
And with cav archers it’s exactly the opposite as you can’t mass them in early castle anyways, so the easy access isn’t anything needed for that kind of unit. That’s why all cav archer UUs see a lot of play.
It’s jsut the game design which leads to this state - and therefore it could be a nice idea to make the winged hussars an “imp upgrade” cause then they wouldn’t be hold back by a bad accessibility.