It can be 'the rules of playing the game' AND also scummy. The overall system may be structured such that it basically forces such behavior. Saying it's scumm

It can be 'the rules of playing the game' AND also scummy. The overall system may be structured such that it basically forces such behavior. Saying it's scummy doesn't mean that this particular seller went out of their way to be scummy or likes acting in that way. But this doesn't stop it being a scummy practice from the consumer's perspective.