I would prefer the world to ban these power hungry graphic cards.. its a colossal waste of energy to use these cards for gaming purpose as well. An energy limit should be imposed to limit how much energy these gaming cards can use.
That would only screw over people who have legitimate uses for over-powered PCs. When you get into "consumer" GPUs that cost $2000+, you are well within what used to be the realm of professional graphics and if a law banned consumer graphics over 300W, AMD and Nvidia would simply launch a mid-range "professional" GPU for deep-pocketed enthusiasts who want those 900W GPUs. Most gamers only play games a few hours a day, GPU power draw isn't a huge deal in the grand scheme of things as GPUs in mainly-gaming rigs are idle or powered down the remainder of the time where they consume about the same power as any other GPU.
If you want to cut wasteful use of resources and energy, start with cutting off billionaires' joyrides to space, personal yacht fleets, people daily-driving 5MPG vehicles for no reason, IRL war games, etc.
Personally, I cannot bear gaming on anything smaller than a 14" monitor and if I could justify the cost of a GPU sufficiently powerful for 4k60, I'd much prefer running the few PC games I play on my 50" 4k TV. If you are happy running games on a 6" smartphone screen, good for you. I have zero interest in that.