RPGMemes

It limits some choices. It limits things that give you a bonus to your d20 roll. There's nothing about it that prevents other vertical growth or any horizontal growth.

You could give players a special feat every level, for example, chosen from stuff that's like "Roll deception vs their passive wisdom. If you succeed, their dexterity becomes the lower of 8 and the current value, and they are vulnerable to sneak attack."

Nothing about bounded accuracy prevents that. The fact that you don't get to pick stuff like that very often is the limiting factor on making powerful, differentiated, characters.