Rifle carry sling methods

[eeyore]

In a recent issue of “ Small Arms Review “ the cover picture shows the combat carry method of the rifle. Two
inch rifle sling parachute cord instead of metal or plastic snaps securing sling to rifle; all the while
carried slung over the shoulder/neck.
The soldier in particular has the length adjusted chest high for forced march carry. While combat ready is
done at just slightly at or a drop below the belt line, easily done in less than one second.
This method seems to be the most comfortable carry,prepared ready and quickest into position method. It will
also keep your rifle with you if you should incur any type of blast concussion, fall down or any other action
that a hand hold might force the loss of weapon. Holding your rifle by hand just doesn’t seem to cut it.
Why doesn't the US military use this method rather than just letting the sling fall loose?
Do any of you out there consider this a better or worse method and if you consider this bad please tell me
why.
eeyore