The only advantage I really see is that the math can be easier in limit hold'em, knowing what your villain can bet. So it may be an easier game to learn at the beginning, but that doesn't mean that it's preparing you for NLHE. I find limit is easier on the bankroll too, as a buy in of about 40 BB is usually sufficient.
If you play live, then knowing how to play both games can be beneficial. There's been many a trip to the casino where the NLHE games were interesting, but the limit tables were full of fish. Since it's not always as easy to find a juicy table live, if you go to small casinos
, being able to play whatever is being dealt is beneficial.
So, no - I don't think you have to learn one to play the other, but I do think that knowing both is a good thing in the long run.