Player rating for tournaments across all installments of Heroes.

Who would even let them do that? There are administrative and forceful methods to put a stop to it, with the help of a coordinator. But even in that case, someone will still end up in last place. Or are you afraid that even in last place, a player will more than compensate for the aging penalty with a 10% bonus, and get a bigger increase than if they went to a weak tournament and took first place? Yes or no? I'm not really getting into the high-level details anymore.

And it's already beneficial for a weak player to be there. The aging penalty from their meager rating is negligible, and the bonus from the tournament's strength will definitely more than compensate for the loss.