As a fan of both Emmure (guilty guilty pleasure) and Volumes maybe I can help illuminate. People here don't like Emmure because their vocalist is often outspoken, blunt, and vulgar. He has no qualms ripping on cheap women and bashing those who have cheated on him and such. Added to that, that their musical structure is often fairly simple and you have a combo that is not going to go well over here. What annoys me is how people will shame Emmure but then praise all these rappers who say and do things along the same lines (almost always worse though). Very hypocritical IMO.
Volumes is definitely a more technical band (especially the LP). Like ZMMO said above, they have that Meshuggah influence that is well respected - "djent". That style is supposed to be very deliberate, repetitive to a building point which a lot of people like. It can be repetitive sounding but as an album experience it usually works out pretty neat.