If you let people camp with a HMG in the sewers then you fucking suck. There are 1001 ways to get rid of a HMGer, including if he's clusterfucked with healing engineerss. I've seen the old version with rooftops, back when I had 2.12. It looked fucking shit. Obviously I never saw it being played, but "intense ground control" basically equates to: Place turret behind HMGer to stop pushback, take healing upgrade, dominate flag. And it's far harder to get rid of the HMGer when he's on a rooftop than in the sewers. Albeit 99% of these problems that are with the rooftops, and by your opinion the sewers too, are related to the HMG.