That's more like "rambo based arguments". Those weapons are being used at combat either being mounted to helicopter/armored vehicle or lay on the ground (on tripod). You can't use them well while just handling in the air otherwise your aim would be terrible.
Firing accurate, short bursts from SAW while standing is not a "rambo based argument". Shooting someone up close from any machinegun while standing is not a "rambo based argument". And yes, being prone improves your odds a lot, just like with a regular rifle.
Second thing is aiming which is done by tracer bullets. First bursts are inaccurative. Unlike smallarms and rifles.
Are you kidding me? Most machineguns have normal sighting devices and can be fitted with optics, first round is as accurate as one shot from a rifle and then the recoil kicks in. Tracers do help, but it matters at the most extreme ranges, which normal rifles don't handle too well. If you go that way you should enhance the range of BGs to that of a sniper rifle, and that would ruin the balance. And yes, I did fire this kind of weapon irl both standing and prone (in single shot mode though).
Considering engine limitation lowering max range would be best option if we want to realisticly nerf them.
The biggest engine limitation is the game does not model firing positions (standing, crouched, prone etc.). Obviously, if you fire at long range, you go prone. Since movement matters less and less the further the range, assuming your character goes prone when whooting at max range is not a bad bet.
