In Season 2, Riot made it so you can't play free week champs in Ranked. This should be changed to be mastery-based.

Note: I'm not talking about Mastery level 5. 2 or 3 would be good enough, which are acquired in ~2 games and ~5 games respectively (depending on grade)

Statistically, if you have never played a champion, you do a lot worse with them. In season 2, Riot looked at that fact and said "well then, it's unfair to your teammates to allow you to play free-week champions in ranked"

You can read the whole discourse here, though it's a 150 page thread, soooo, yeah.

Anyway, the point was, that limiting players from playing free week champions was the only way, at the time, to establish a "minimum experience" rule.

But now there's mastery. With Mastery to establish a minimum experience requirement, people can play free week champions if they put in the time and effort to learn them in normal games, even if they don't have the IP to buy them, AND there would be a more effective way of keeping people from ruining other people's experiences by playing champions they don't actually know how to play.

The only downside would be how it impacts trading, but considering trading is already limited by mutual champion ownership, I would say this is an acceptable downside, and that the trading system in general needs a rework that would remove the "mutual champion ownership" requirement anyway, like "picking for player", or simply being able to trade positions in champion select, but that's another discussion for another day.

TLDR: Changed the Ranked ownership restriction to a mastery-based restriction.