I can't believe that the decision makers in the EU even heard of any of this, or that they would care even if they did. The power reduction regulations are targeting things that make a big difference overall. They may individually not be as much as a pimped out PC, but there are so many more of them. Standby power for example, applies to most things connected to power. How many of these devices do we each individually have? Even if you're saving a fraction of a watt on each, multiplied by billions* of these devices across Europe, the savings are real and significant. More than 2 way SLI/crossfire PCs? Even if you ran them at full power, it wouldn't make a dent. *estimate based on European population, and that each person would on average have far more than one device.
Nvidia's limitation is probably their own, and not due to an external influence. I think in part of nvidia's problem was that scaling wasn't there beyond 2 cards, and it became more something to do for bragging rights only. The effort it took for them to support that wasn't worth their time. If new APIs or programming methods allow better scaling to be made use of, I can see them reversing that.
AMD, who knows. Do they scale better beyond 2 cards? That's probably still the bigger limitation. It might be interesting to see what happens after Vega drops as indication.