Someone saw "Shooter" I think
That's always been my interpretation of the SFP. Honestly, if you *want* to carry thirty pounds of SFP and firearm around on your chest, be my guest. That's usually where I sling ammo. Or a hawaiian shirt, if I'm trying not to get arrested.
If you wanted to, you could drag around a .30 caliber machinegun attached to a deployed tripod. I'd probably choose to carry it on my back, which might make quick deployment difficult, but that's not the point. People can drag around fairly bulky 30+ pound objects if they really want to.
Would I want to? No. I've got better things to be doing with my hands than manhandling a tripod and machinegun around all the time. Could I, in theory? Sure. I can also, in theory, fire a .50 caliber machine gun from the hip. Doesn't mean it's a good idea.