Look, there are obviously clues spread all over the books. The dream about the Tower of Joy is a great one. It still requires a lot conjecture on the part of the reader.

By itself, the events that we know of surrounding Ned and Lyanna at the Tower are fragmented and could still potentially mean something other than what has been theorised.

I won't argue that the evidence isn't there (I agree with the theory, remember?). I am merely pointing out that the clues that are seeded regarding Jon's heritage are more ambiguous and fragmented than say, I don't know, Bran catching Jaime and Cersei in the act, Joffrey's complete lack of resemblance to Robert, etc. I wouldn't have put them in the same sentence.

It would have been like comparing that knowing that Demandred was in Shara prior to the reveal was the same as knowing Moiraine would be rescued from the Tower of Ghenjei. Looking back, there's evidence for both reveals. One, however, was a lot more obvious.