of course the theory didn't take anything away from books 3+, because it's based on info that was mostly from the first book
but that info (Ned's dream about the Tower of Joy and such) hasn't really been presented on the show. but if the theory is true (or semi-true...), and as important as it seems, the show will have to cover it. the story Littlefinger tells Sansa in the last episode, especially the part about the moment "all the smiles died", is directly from Ned's memories while locked up in the first book. my kind of outside-the-box perspective on that is that the show knows it's viewers have short attention spans, so they're presenting this info now because they plan on doing something with it soon. all of a sudden, two Rhaegar stories in one episode...
to be clear, if cats ask you to PM them or whatever, then give them what they want. for that matter, if they want to get spoiled, the info is easy enough to find on their own