Gaming Laptops are somewhat overrated. They are typically non-upgradable, or if there are upgrades, they are either limited or proprietary. for example, you'd never be able to upgrade that to a GTX 1070. Further, they heavily compromise battery life for performance; that laptop get's a little over 3 hours of battery life with medium usage; and only 2 if actually using it for playing Games. Comapre that to the 10 hours I get on my Thinkpad T550 and you can see the heavy compromises made in the name of "Gaming".
Not to say there isn't a reason to ever get one, just that it's a weird niche because the "top-end" changes so frequently that even today in some ways that system is out of date. Eventually the laptop will be "old tech" and you'll still be left with it's limitations like poor battery life, which will get worse as it ages as well.
With a desktop you lose the portability (which even if just symbiotic with AC outlets, is still an advantage) but you get a more industry standard configuration which you can not only upgreade but even think ahead to future upgrades. Eg- if you get a 970, you can upgrade later to a 1070; if you get a 1070, you can upgrade to some new nvidia or AMD graphics card that is better in the future; if you get 2 8GB sticks of RAM for a motherboard with 4 RAM slots, you can later slap in another 2 8GB sticks to max it out to 32GB, etcand these upgrades tend to be more affordable for a desktop system even where they are possible for a laptop.