If someone today solves an obscure problem of similar difficulty to Dijkstra's graph search, they won't be called great anything. It is the impact that matters, not the difficulty of the problem or the IQ of the inventor. Great scientists, philosophers and artists had the foresight, luck, and ability to develop something that subsequently had a massive impact on the world.
A point in the article that I agree with is that great philosophers shouldn't be treated as flawless geniuses. Great people of the past made massively impactful contributions, but that doesn't make them the ultimate authority on their field. Answers to today's problems aren't going to be found by disecting footnotes of Aristotle, Turing or Einstein, but in work of people who will make contributions today that will shape the future.