There's no need to know the actual balance, just a boolean value that is returned true if the account balance is above the amount requested, and false if it isn

There's no need to know the actual balance, just a boolean value that is returned true if the account balance is above the amount requested, and false if it isn't. It's true that it could be abused by "bruteforce", but this could be throttled or put in a cooldown if too many requests are made to avoid such a scenario.