Regarding Champion Mastery

When looking at the current champion mastery system holistically, the system makes sense. You play the champion in PvP matches against other players and over time you build a mastery score with that champion. After reaching a certain point, you then need to prove yourself on the champion by earning S- or higher ranked scores in games to continue to level up your mastery score with the champion. I personally really like this concept because it is not just a grind of another kind of XP to level it up, it changes to an achievement based progression which is far more satisfying as you earn the mastery tokens. As you progress with the levels of mastery, you unlock different ways to show off your mastery to other players and have somewhat meaningful accomplishment-based rewards for mastering your favorite champions.

Here is where the current system loses me. While I understand why the champion mastery system is locked to PvP play because you can only learn so much about the mechanics and truly master the gameplay of the champion while playing around in the practice tool or playing against AI Bots (there is something to be said about having to make reactionary/predictory decisions and match them mechanically), the system has shifts after reaching level 5. At current, playing any variation of PvP match, you can build mastery for the champion you play (SR, TT, HA, etc) up until level 5 mastery. Then when you get to the point (level 5) that requires S- or higher performance, this does not apply to all maps/variants (specifically ARAM from my personal experience).

While I understand this is the core game mode of League of Legends, my reasoning is that if you allow players to build mastery playing other PvP variants (which I completely agree with because they are truly learning/mastering the champion as they test themselves against other players), why then limit their ability to maximize their mastery levels to only the SR (and possibly TT) map variants? While there is a place for players to test themselves against others in Ranked (which is like a type of player mastery rather than just champion mastery), I do not necessarily think that this should be the standard by which you gauge champion mastery specifically, especially for those players who prefer the other maps/variants and have been earning champion mastery through these variants all along until the level 5 plateau.

Would it be possible for Riot to modify the mastery token system to include the other standard/permanent PvP variants? It's just really frustrating to build a mastery on your favorite game variants (specifically ARAM for me) to hit a plateau after feeling accomplished leveling up your champion mastery on these maps because you're not playing Normals or Ranked on Summoner's Rift.