Perhaps he means that in comparison to the rest of society (or the army say) promotion was not entirely due to who daddy was and how much money he had?

That's got to be part of it. I think he's also pointing to the (particularly compared to the Army and land life) reasonable numbers of captains who made it out of the ratings -- there were only something like three of them during the classic Age of Sail who reached the rank of flag admiral, but after you got vested with post rank, that was just a straight-up matter of seniority. (ie: a function of the fact that most of them hit post rank v. late and consequently just didn't live long enough to hit the high echelon.)

So. Yeah. I gue I kind of agree with him if you look at it slant-wise, but still. I'm ausming that you've got to show a LOT more brilliance if you're the son of a blacksmith than, you know. If you're an Earl's son.