I agree with your sentiment that he is overblown but, humans have to focus on just one or two pieces of the puzzle, not many people have the mental capacity for holding the large scale unfolding of ideas and history. And no one, even the most brilliantly right-brained among us could see it all all at once. We always choose an example or two, and for thinkers (or anybody) it's the luck of the draw whether they get remembered or not.

Thus, mystifying and glorifying Marx while ignoring the fundamentally erroneous parts of his thinking would be the last thing to do

If we didn't do this we would have nobody to celebrate, since almost everyone is found to be fundamentally erroneous given enough time. We might have to take each person's ideas that we support apart from other aspects to make them work (two obvious examples are Thomas Jefferson and Isaac Newton). I am not saying this because I don't think it's important to teach people to be critical of their 'heros', because I think this article is a really important and sorely missing part of the conversation. I just say the above things in case you are personally frustrated with why people do what they do, like I am haha. Maybe we will eventually evolve to a less single focused species, and the idea of glorifying ideas like they existed in vacuums will end.