We definitely need higher levels than 5 when it comes to champion mastery.

theoretically it takes like 26 wins to get to level 5. if you try hard enough you can get there in 3 days. that doesn't seem like a "mastery" if you look at all the challenger players who have "main champions" they have hundreads and sometimes thousands of games played and they get the same rewards as those who play like 50 games