To let me know what the Shulchan Aruch says, a friend is enough. Paskenning means his ????? ???? confess into play.
For some people the rabbi is just a friend who knows what the Shulchan Aruch says. (Lav davka Shulchan Aruch; I mean that he knows the relevant Torah sources.)
About my supposed irony, I think you are still misunderstanding my point. All I said is that the pasuk sets up a system where there is one centralized authority which everyone is beholden to, and it would therefore be ironic to use that as a source for each person to follow his rabbi, considering that that’s the exact opposite of what the pasuk intended. If you are trying to get as close as possible to the ideal, you can get a lot closer than having everyone pick a rabbi to follow. For instance, let’s say the current ratio is one rabbi for every 50 practitioners. Well if we eliminate half the rabbis, and make the ratio one rabbi for every 100 practitioners, it is more centralized.
Again, this is not to say that people should not follow a rabbi; it is to say that the reason why some people follow a rabbi might be different then the one popa suggested, and the difference in reasons might have practical ramifications regarding the circumstances in which one would not follow his rabbi.