Mastery Tokens before rank 5

I think it would be nice if we could earn mastery tokens before we hit rank 5. Why do all the S grades we have obtained before this rank mean nothing? Why does playing 50 B grade games and subsequently 2 S grade games demonstrate higher mastery than when you get 2 S grades in the games you play towards rank 5?

I recently switched roles to support, which means a lot of new champions for me to play. I have to level these champions up from rank 0; and since I'm playing a variety of champions it will take a while before I hit mastery rank 5. I have already gotten multiple S grades, but unfortunately they all go to waste as I'm not rank 5 yet. Why is this? If I don't have any chests available to unlock, it is pretty sour.

If Mastery tokens would be considered as too much, I would even be fine with token fragments. You could combine 2-3 fragments into a full token. Of course you should be able to dissenchant these fragments because they become useless once you hit rank 5 (as you'll be earning tokens instead of fragments from then on). Dissenchanting in a bit of BE can in turn help with unlocking the next mastery rank.