The problem being that oversimplification is misleading. For example, Ashe's kit is designed to kite, but most new players don't really know how exactly her kit = kiting, if they even know what kiting means.
They won't know off the bat that Ashe's main method of kiting doesn't affect dashes or blinks, while similarly they won't know off the bat that Kalista is also a kiting champion, but just kites in a different way, and hers DOES affect dashes or blinks. They also won't know how to effectively cancel the useless portion of auto attack animations (especially not on purpose), which is really what kiting mostly boils down to, and is something that EVERY ranged champion can do, not just Ashe.
What exactly is a long range stun to a new player? Can she just stun people at range whenever she wants? Is it a skillshot? Does it stun multiple people or just one? How long range is it? If it's a "long range" stun, can she use it at close range? Etc etc.
And that's just with one of the simplest champions in the game. I don't even know how you'd begin to simplify Azir, Zed, or any of the newer champions.
THEN we get into the fact that oversimplification leads to overlap. Talon and Zed are largely meant to fulfill the same role, but are somewhat different in how they do so. If we were to implement such an idea, players would get the idea that two champions that are radically different are somewhat similar.
Going back to the fighting game example, anybody who's never played MvC3 or KOFXIII is going to have absolutely NO idea how Zero or Claw Iori really operates based on those descriptions alone, even though more experienced players will know what that means and what that character really does based on experience alone.