Regardless of anything to do with the meat and potatoes of this particular suggestion, or RMT, or anything like that, it's worth mentioning that doing Account-Wide reward systems in general in this game (in a non-hacky, clunky way that would make the game worse) is... a nightmare, to put it extremely lightly. Unless some signiiiiificant work happens behind the scenes, most account-wide rewards are off the table for the foreseeable future. The very few account-wide things we do have in the game are problematic as-is on the back end and, far as I understand, an active detriment to the actual performance of the game as a whole.
Never say never, of course. Trust me when I say I'd love to be able to do more account-wide reward structures, and I'm certainly not alone in that on the development team. But yeah, I'd advise extremely tempered expectations on any and all account-wide feature suggestions.