I'm sure most people have noticed the prices on cards have gone up. A large part of it is because of people using gaming cards for mining. It's also led to a bunch of bad resell of these cards to individuals who don't know better to look out for them.
Mining doesn't require the full resource of gaming cards.
It's also possible to detect mining behavior and code.
One could create gaming cards that thus could not run mining code.
A separate set of cards / could be made with mining as the primary focus.
This would then create two separate markets for AMD which they could create separate pricing for. That would give AMD better control over supply, and better serve their customers.
The same chips can be used it would just need a change to the bios for the different cards. Having that two different bios would also allow better performance tuning for miners on their card specific cards.