Even without perks, the higher levels would result in the characters having way better stats which would really imbalance the game. They might tweak the exp-curve though, so that reaching level will be more of an achievement.
You’ll start to notice it once you keep buffing melee and defence skill, combined with perks that buff them even further (nimble, dodge, etc). A properly build sword-master can have a melee defence of well over a hundred, though you’ll always want to avoid arrows.
