Consider the source. The Army has always been wimps. That is why they wear "fatigues," they are always tired. So it doesn't surprise me that the pathetic Army pansies would list a single-man operated firearm as a "crew served" weapon. No doubt the Army also needs help with throwing grenades.
When I served in the Marine Corps the M-60E1 was considered a "crew served" weapon system because it required two to operate the weapon properly. However, advances in metal technology have made the M-60E3 half the weight and no longer requiring barrel changes. So the modern M-60E3 is not a "crew served" weapon system (except for maybe in the Army).
As the biggest guy in the platoon, I got saddled with carrying and operating the M-60E1. My military service also predates the M-249. It is not a firearm I would have used. If it doesn't fire at least 7.62mm, I'm not interested in using it. Always use the right tool for the job, and 5.56mm doesn't cut the mustard.