What if you could get any skins through playing a champ intensely?

So i was thinking, as a otp myself, that not being able to get a legendary/rare skin for a champion that you got hundreds of games off can be really frustrating. So what if riot made a system using mastery points and skins. so it could be like this: the moment you hit lets say 1000 k or 500 k mastery points on a champ, which really requires dedication, you got to choose any of the skins for the champion ever released. This would be really nice, since skins like the pax skins and urf warwick, in my opinion, should stay really, really rare, while still giving the players an opportunity to get that sweet skin for a champion you have dedicated so much to. Just a thought.