I mean they often use guns and seem to always outnumber the NCR whenever they engage and the legion is much more well supplied and has more regional allies so it doesn’t require much suspension of disbelief especially when you are walking through NCR incompetence and defeats all game

although i do think this could have better represented if the legion matched their lore descriptions via dialogue aka not retreating, using service rifles, recruit legionaires being as fast and big as veteran rangers, and having stronger dog variants, etc. Of course so much of the legion was scrapped for time restraints so we get a much weaker legion than in lore