Because gpu is almost entirely irrelevant for vanilla minecraft, and most modding. The only time GPU really would ever be a bottleneck is running large (256x) resource/texture packs or running complex shaders.
7700hq isn't the slowest processor ever but it isn't very fast. It's not really a gaming processor for games like minecraft that are single-thread intensive. Its base clocks are only 2.8ghz (although yes it can turbo up to 3.8ghz, maybe look at your power settings) and being a 4 core processor doesn't mean much to minecraft besides "having chrome or other programs running in the background will slow minecraft down less".
I'd say with your setup that fps sounds about right, but you could install several (clientside) performance mods if you really want that extra fps (not that there's literally any benefit to it. you should be capping your game fps at monitor refresh rate + 5 or so)
I am able to run above 200 Mods on MC 1.12.2 with Cinematic Kuda Shaders (Or Cuda, I can’t remember), Sphax PureBDCraft 256x (512x @ 22FPS), and my basic Video Settings were: Fancy Graphics, 14 Chunks Render Distance, Smooth Lighting COMPLETELY OFF...
And my Tower Specs are very similar:
HOTBOX, has 16GB DDR4 RAM, NVMe M.2 SSD + 2 other disks, NVIDIA GTX 1070 8GB, Intel Core i7 7700k @ 4.8GHz. just in case that was needed.
This guy was saying his unmodded with forge installed was pulling lower fps than he sees other people use. He's using a CPU considerably slower than the one you're using, and that is why. Your tower specs are nowhere near this guys.