Okay, one cannot compare games which are not available for Macs. It also depends on the game. Some games run better off CPU (WoW Legion) while others run better off GPU. You also need to remember, Apple sucks bigly when it comes to drivers for their GPU. Add into the fact AMD also sucks with their own drivers vs. Nvidia, which they provide Macs drivers now and regularly updated. So yes, MBPs (including mine) really is quite subpar vs. a comparable PC w/ Nvidia.
I don't think the driver thing is nearly as true now as it used to be.
And far as power usage, that's a silly thing to bring up. Especially when there are laptops out there equally thin but better internal components. Apple simply is, once again 3-5 years behind PCs. Aaannd, lest we forget about Metal being buggy and not adopted by the industry as a whole so there's that setback...
Uh...
"3-5 years"? No. Skylake's pretty recent. rx460 is also pretty recent. "3-5 years ago" did not get you 14nm process for your GPU.
Now, if you want to claim that Apple's on the low end of the power curve, well, sure. I'm not 100% sure that my three-year-old gaming laptop will still be faster than the new MBP, but I won't be at all
surprised if it is. (It cost me something like $950, too.) And it does use more power -- 135W or so, instead of 85. And if I got a new machine, it'd absolutely run rings around anything Apple is likely to ship.
But that's not "years behind". That's "not willing to make a machine big enough to dissipate that much heat."
To the OP, yes if you want a decent laptop for gaming, then go PC all the way, get a modern GPU that isn't under clocked to the max and save probably $1k+.
This is pretty much the case. After a particularly unsuccessful attempt at getting a "gaming-capable" mac laptop, I stopped trying. Now instead of trying to get those last little bits of very expensive performance from Apple, I get cheaper stuff from Apple and have enough money left over to get a PC gaming laptop every couple-few years.
And it's not remotely a replacement for the Mac. I think the maximum thickness of the (somewhat wedge-shaped) gaming laptop I'm currently using is probably 1.5" or so. It's got air vents that are taller than the new MBPs. But! It can run games with pretty tolerable performance, it has two drive bays so I can put in a second SSD, memory is upgradeable, and it runs quieter under higher load than any of the MBP-family machines I've had in the last decade.
... Which is to say, if Apple charged $1k for a MacOS license, I'd probably get a high-end gaming laptop and a $1k MacOS license, and be happier with the results.