I generally consider the PCs to special. Not only do the vast majority of people not level up, they actually CAN'T. The form it takes varies between campaigns and sometimes it is more explicit than other times, but generally PCs and powerful NPCs exist in a class of their own. They are the supers, even if the PCs are just learning that to be true in the early levels. So in the end, in your scenario, it matters to the PCs because they are the only ones capable of putting these depraved "supers" in their place.
I really like this thought, and in truth, have desired it to be baked into the ruleset more clearly. The fact that there is a range of "bad guys" that span the power spectrum, each with powers similar to PCs makes me always think otherwise - especially when said bad guys are everywhere. Sure, the PC can cast fly, and extraordinary ability of you think about it, but so can the goblin shaman or cultist wizard or the other fifty monsters that have wings.I see it more or less the same way. I wouldn't say can't I would say wont. In the Richard gear and Seas Connery King Arthur movie there was a line that stuck with me "Oh, anyone can learn this, you just need to watch, wait for the right moment, and not care that if you fail you die" followed by the guy who wanted to learn deciding not to.
Heroes, and main cast PC/NPC are not born... they are made. something happened (maybe in game maybe in backstory) that made you do something daring and crazy and maybe even suicidal (and in the case of me and my buddies most likely something stupid) and from that you got a little bit better... and you continued on that path were most would turn from it. That is what 'leveling' means in most of my worlds... learning and growing down a rare path.
But that is a great discussion to be had - whether players and DMs like the zero to somewhat hero or zero to superhero or hero to superhero.