I definitely disagree here. What matters for mobile is power consumption. Capabilities can be pretty easily implemented...if you disagree, ask Apple. They have seemingly nailed it (with a few unrelated limitations).

Mobile vendors insisting on using closed, proprietary drivers that they refuse to constantly update/stay on top of is the actual issue. If you have a GPU capable of cutting edge graphics, you have to have a top notch driver stack. Nobody gets this right except AMD and NVIDIA (and both have their flaws). Apple doesn't even come close, and they are ahead of everyone else except AMD/NVIDIA. AMD seems to do it the best, NVIDIA, a distant second, Apple 3rd, and everyone else 10th.