That said, you are touching on something I left implicit in my original post. Yes, there is a really small chance that you are the smartest person with the most relevant experience relative to a given problem to approach it. And, if this is the case, that is your valid answer to why you haven't seen someone else do it before. But for most people this is simply not the case and even for the people you are thinking of now as the smartest should assume it isn't the case, at least at first.
If analyzing the situation and doing research legitimately leads you to "I am better/luckier than everyone else who's approached this", good for you because you're off to a great start.
As far as Larry Page goes, a sibling post said that pg, to name one person, had something very similar to PageRank futher driving in the point that you usually can't count on being the first to figure out a solution. But, regardless, it absolutely would have been fair to ask Larry those same questions at the time he was founding Google. No matter how smart you are, due diligence is a key concept.