It is true that in reality there was no such formal organisation of pirates, and if you don't like the idea of joining such a band and gaining "ranks", there's a very simple solution, which is the one I normally use - don't join!
The idea of making all the "rank" names the same is a lot sillier than keeping the existing names. You'd start off as "Brother of the Coast", be promoted to "Brother of the Coast", and when you reach rank 12 you'd gain the lofty title of "Brother of the Coast".
As for making the rank names invisible, what's the point? Wasn't the whole idea of the "Brotherhood" to give pirate players the opportunity to gain "ranks" the same way as privateers in the service of nations?