I think going one layer lower - the fundamental issue is that the internet drives people to unrealistic perceptions of the competence of others. Think about all of the undeniably brilliant people that have been involved in software over the past 40 years, and how many of them used hash tables in performance critical environments. Let alone mathematicians and others using them in applied domains. And you think there's something fundamental that all of these people just somehow missed?

The argument of 'if that's such a good idea, why wouldn't somebody have just done it already?' seems to have grown exponentially with the advent of the internet. And I think it's because the visibility of competence of other's became so much more clear. For those who lived through e.g. Carmack's Golden Age you knew you were never going to be half the coder he was, at least based on the image he successfully crafted. That 'slight' at the end is not to say he wasn't a brilliant developer or even perhaps the best in the world at his peak, but rather that brilliance + image crafting creates this Gargantuan beast of infallibility and exceptionalism that just doesn't really exist in reality. I think it's from this exact phenomena that you also get the practical fetishism of expertise.