Preventing people to "practice" champs in ranked - a bad idea?

Hey, just a random light bulb from the top of my head. You know how some people play unexperienced champs and practice them in ranked instead of in normals, which pisses off many people? I just remembered that recently Riot made the champion experience level stuff (the thing which gives you grades of A, B, Cs after each game). How about, you can only play champs with experience level 3 or higher (numbers can change up or down) in ranked games? Of course letting people only play exp level 6 (the ctrl 6 thing) champs is kinda too much, but level 3 or higher... that should be enough. I mean, shouldn't people at least be playing something they practiced from normal games in ranked?

This was just a random thought, this does not really affect me because I don't play ranked these days. But since Riot made that champion level and stuff, maybe this will help other people out there. Is it a bad idea? Just curious.