I think this thread is really about two different things -- first, the usefulness, the practical utility of nautical terminology. Yeah yeah, bathroom/head, maybe that one is not critical, but I think that's a rare exception. About 9,000 posts have pretty solidly demonstrated that nautical terminology has a crystal clear practical utility and purpose, just as specific terminology does in lots of other specialized areas in life, in multiple languages.
I think the other issue though -- and maybe this is the real reason this thread has been so active -- is the charge that people who use it are being snobby or clubby or purposely obscure. I don't buy that argument either, in general. My wife and I did that touristy-but-fun Maine schooner thing one summer. Spent a week on a historic schooner, sleeping in a plywood bunk on a creaky ship with cold rainwater dripping through a loose deck prism onto my head. (DECK PRISM -- I have no idea what else you'd call it.) I thought I was pretty up to speed on my salty vocabulary but that rigging made me learn another Melville-novel's worth of nautical terms. The owners and crew and (most of) the other passengers weren't being snobby or clubby or purposely obscure. Granted, there was one obnoxious passenger who learned it and used it just to be a bossy jerk know-it-all, but he quickly became the butt of jokes. In fact some of us even made up our own nautical-sounding terms that were actually nonsense just to play with his head. And okay, I did want to whack his skull with a belaying pin, but I resisted the urge.
In short, yes, like any group of humans, when it comes to boats you have good reasonable sensible people and you have jerks, but in my experience the clubby snobby people are the minority, at least for those who actually run and maintain their own boats.