don’t forget the security problems that would create.
if you are able to trade cards you are effectively able to trade money. so your account is suddenly “worth” something in real currency and not just pixels.
and at that moment the game would be swarmed by hackers selling your cards.
and it is not just the personal loss. the developers have to implement new systems to support hacked customers, add new safety features and ban bots (who could now farm real money even with losing, so they don’t even have to be good).
and that would probably just the tip of it. bigger games with those problems like mmos have large teams just to deal with those issues. i doubt a small developer could or should be bothered to invest in that kind of manpower for such a relatively small benefit.
