Were the army or Marines truly blind meritocracies at every level, even within the officer corps? Because that would be impressive, and a sad thing to lose for vanity metrics.
I was enlisted in the Army, and an officer in the Marine Corps. No organization is perfect but by-and-large, yes, I found even the officer ranks to be reasonably meritocratic. If anything the organization's biases were caused by your career background: Infantry Officers rule the Corps as a whole. Fighter pilots rule the Marine Aircraft Wings; every other professional specialty is definitely a second-class citizen.