I can always tell the good zed players from the bad ones. The good ones will throw their shadow at you, switch places and use auto attack e and q very quick and ult if he's not fed enough. Bad zed players just ult e q and press r again.
i'm not saying good zed players won't start ult, because there are plenty of places to start with ult, such as under tower. But bad zed's will almost always start r anywhere. on the map. Problem is how forgiving zed's kit is to such players.
Again I'M NOT SAYING GOOD ZED PLAYERS DON'T START R.
Edit: I think some of you don't under the term skill ceiling. Think of it like a piano player. You can be bad, average, and expert. Average and expert pianists can most likely play a simple song flawlessly. But only experts will play the most difficult songs because that's how far they've taken their skill. Zed is that champ that is a simple song.