This is probably true, yet largely irrelevant. Whether someone's ideas are obvious to them or not matters little compared to how much impact those ideas have.
It seems particularly relevant for mental or theoretical work where choosing the right approach has a great deal of leverage. If "all" you have to do is "just" look at a problem in a certain way, or examine the equation like so, or frame the issue from a particular viewpoint, then the resulting breakthrough may simultaneously be quite stunning to people who didn't think of it and quite obvious to people who did. Changing your viewpoint is as easy as deciding to do so - it's a task that doesn't even require the mental effort of, say, memorizing the dictionary, or similar feats of mental and memetic agility. But knowing that you can change your viewpoint, and choosing exactly the right viewpoint to use, is an extraordinary ability that not everyone has.