I am not saying that to belittle the man in any sort of way, or diminish his accomplishments, I am just simply saying it shouldn't be surprising that people haven't heard of some other people, despite how famous others think he or she might be. Pretty sure there is an XKCD for this. I have my categories of people where I would react the same way ("What do you mean you have never heard of Carl Sassenrath!?" as an example).