[Suhiir]

No offense taken.
But, it is heresy...

There's a reason the United States rates two OOBs.
The US Army/US Air Force is a totally different entity then the USMC/US Navy.

The US Army (and it's OOB) are generally armor heavy with limited air support. The US Army is designed/intended for sustained combat operations.

The USMC (and to an extent it's OOB) is infantry heavy with much greater helo/air support (USMC/USN air work very closely together, in fact US carriers often have a USMC squadron aboard).
The USMC is designed/intended for fast/first reaction to seize/establish a forward base to allow the much bulkier/slower to react to "now" requirements US Army to get it's gear and people in place. The USMC is designed for limited duration (90 day or less) high intensity operations.

Does this mean the US Army can't react first or the USMC can't do sustained operations?
Of course not.
But, they are two separate animals. And each uses some equipment unique to it that the other doesn't even have (or in very limited quantities).