There is nothing wrong with the fact that he didn't know it either. Only willful ignorance is a sin, not accidental ignorance. Nobody can know everything, you shouldn't judge someone for prioritizing different knowledge than you.
The state of history education is abysmal, at least in the US.
I sure as hell was not taught enough (and most of what I was taught, prior to high school history classes, was whitewashed propaganda. Things like "The Russian space program was awful", "The Native Americans and settlers got along swimmingly", or "Columbus thought the Earth was flat". Stuff no adult familiar with the material believes for a moment, but that we teach children anyway.)
The meme I more recall is "Columbus uniquely thought the Earth was round." Really, most people thought the Earth was round; Columbus thought the Earth was 1/3 its actual size...
Knowing that Hitler heavily leveraged propaganda to further his cause might be of use to an individual. I don't think knowing Goebbels' name is necessary for learning such lessons though.
Possibly true, though I would question the quality of any lesson about Nazi propaganda that did not mention Goebbels' name. If you are doing the "3-lesson 10,000 foot overview" of the 1930s and 40s then I can see how Goebbels' would escape mention, but otherwise he is definitely in the top 10 figures to mention.
I don't know about you, but I tend to forget details that I don't regularly use. I have learned about Goebbels and forgotten his name at least once. I focus primarily on remembering the lessons learned because I know I am likely to forget details such as names. I can usually remember the overall lesson learned because it resonates with my intuition and world knowledge.
Not knowing the names of prominent figures is some (quite inconclusive) evidence of insufficient familiarity. Any encouragement of the type I was speaking of should recognize that (and should be polite on other counts as well, of course) or is not entirely appropriate.
