I feel its a matter of perspective.
Learning everything those characters have to offer is much harder than doing the same for endevor but those characters have much simpler and effective options that work. For example you dont see iidas doing beta, alpha, beta often because alpha alpha beta is much easier and safer with iida being a much better character in general hes allowed to get away with simpler tactics most of the time.
Endevor is not allowed to do this. Endevor cannot just play easy you have to play everything to its maximum but playing endevor to his maximum is imo easier than playing many other characters to their maximums.
Mnt lady can just rely on big form cheese but if you play her small form to its maximum shes a monster. Theres just often little need to do so when simpler options exist.
I still think kendo beats out every character in both of those categories tho. She cant ever just take it easy. You have to always play to her max and playing to her max is quite difficult to do