Because some things just push reality. I mean, my resume for the NCR is better than any other soldier in history:

-Singlehandedly killed Caesar

-Singlehandedly killed Mr. House

-Singlehandedly killed an entire chapter of the Brotherhood of Steel

-Singlehandedly convinced an entire settlement with much artillery to aid the NCR

-Is only "Liked"

I should be a [censored] general by now. And in the end, I'm only given a fancy medal? What a load. As much as I think the NCR is the best option, it's not as

With the Legion, it makes more sense. I do all this stuff and save Caesar's life, but he's a megalomaniac and has an image to keep, and can't allow anyone else to seem as powerful or more powerful than him. And in the end, you get coins minted after you, so that's cool.

Mr. House has the best gratitude, though.

NCR soldiers themselves admit this.

"You know, if you were serving, you're probably halfway to general by now"

But you weren't. In fact, if you were serving, you probably won't be able to do all those, you're stuck sniping/shooting/shoving things up Legion hindquarters

yes you could only rise through ranks if you enlisted in the ncr who would probably shove you in a corner in the map and keep you there dispite all you did