Haha thats a good one, but I haven't heard someone saying "Man, I think firebolt dealing 1d10 is too much, my character's firebolt will deal 1d2 instead"
Policing in terms of roleplay decisions, sure, but rules are written and only in some occasions are open for interpretation. And there is DM to help with any confusion.
My experience as a DM has shown me that most players care more about playing what they like and what appeals to them on an emotional level rather than what is numerically the most potent builds. That’s the very definition of policing yourself for game balance.
One of the players in my last game was a nerdy wild magic barbarian / wizard. I have a player in my current campaign who is a wizard trying to keep that a secret my lying to the party and pretending he is a monk. Everybody has the option to play coffeelock and hexadin, but nobody ever does in my games.