Maybe Emplacements should be considered unviable? Or purely defensive?
The thing about ISGs is, unlike mortar pits, they're not as survivable and can be reclaimed by opponent troops. Mortar pits on the other hand, have lots of protection and normally dies when decrewed.
if you play against moderately good player it's almost impossible to steal one unless your opponent plays like a retard.
But actually, the thing is 100 % opposite of what you say that, unlike mortar pits ISGs are absolutely survival, and almost never die, cause they are usually sitting beside medic trucks being constantly healed and repaired of required and can move away easily when counter barraged, and often protected by the flak truck which makes it not flank-able in that stage of the game
because in order to harass that position you need to first kill the flak truck and if you try to kill the flak truck with your AT gun, it dies to a few shots of ISGs too quickly and you hand in your AT gun to your opponent as well
Honesly, it's way too broken at the moment