More people = more cheats
Also, most people that got to Global on 2015 got fucked by the system down to LEM and if you got a few losses out of that you go back to DMG, from DMG up to Global is kinda hard when the system makes it even harder.
Still tho, you can make it, but at least in my opinion, why the fuck would you try to get up there again after you didn't really demote but the system fucked you up.
Anyway, is possible to get to global with -60 FPS, but the truth is that it's hard to play with players that go around with 144hz monitors, 5 ping and 300FPS.
But tbh, most people at this game is awful on MM, the good players want to become pros so they go to 3rd party systems, also, we're talking about Nova Master, not really global, you should get to DMG no troubles with 150 FPS, just find a suiting setting and start playing a selected group of maps, try to get some fucking friends to play and bindToggle voice_enable for those fucking russians.