So you want to pay twice the money for a mac, even when a non-gaming PC is twice as good.
At least there is a chance of a non-gaming PC playing decent games, rather than a mac that will play none.
This laptop is living proof.
Take a look at NVIDIA's GTX 690 and Quadro 6000. GTX 690 supplies 10x more power than the Quadro 6000 (and for the matter, any other Quadro). Why? Because of performances. Quadro 6k's aren't made for gaming but for actual work, like architecture, 3D rendering etc. is done better on the Quadro rather than the GTX 690, regardless of being a dozen times less powerful. Each thing is optimized for other uses.
Mac's have more professional-grade and work-grade software that runs way better on the Mac than on the PC. Regardless if the hardware is the same, the brain (motherboard) also comes in handy.
Not saying you can't just get a Windows either, but Windows runs more crap on professional stuff if you don't load it with good hardware like Quadro's. But that ends up pricing it double from a Mac.
(Also for the record, GTX 690 costs $1000. Quardo 6000 costs $5000.).