What part of this is any advantage to anybody ever other than feeding the egos of your more toxic players? If your a genius, you wouldn't want any mastery shown at all. That's giving the enemy team an extra advantage on who they need to focus more. Second, I'm pretty sure if anybody pays for this, they are immediately going to be slaughtered like the gold mechs from Mech Warrior Online. Anybody who buys an "achievement" just to waggle it in your face deserves to die right?
Nah I can't see any point to paying for this and I'm seriously questioning your methods to make money at this point. At least stick within the moral boundaries.
On second thought, here's an example of a game pulling it off while offering a reason to buy it. Counter Strike. You can buy a skin with a stat tracker on it.