I'm not trying to be a dick, but "Chair Force" isn't a joke. I've been to the USAF Customer Service section on a base. Whole swathes of the Air Force can be basically just another government bureaucracy with a uniform. The US Army can be a huge bloated makework program.

The Marines aren't intelligent. But the power of the USMC's cultural institution is the key difference. "Aggression" is not a bad word, but "individual" is. The focus on pride, excellence, and competition, make it not suitable for most Leftist rhetoric. Globalist rhetoric, as Mattis shows, it's more than possible. And although plenty of Marines don't necessarily live up to that level of excellence, there's such a huge social pressure to preform that it can't be easily co-opted by Leftist narratives that would work quite easily on civilians. "Rights, Democracy, Equality, Love" just don't work as rhetorical devices when the response is: "Fuck your rights and call your congressman, this isn't a democracy, we're not equal we're better, and violence of action is much more effective than love."