Earlier quoted context omitted.
Let me put it this way: Can you really blame someone for not knowing a historical fact that is completely irrelevant to their life, especially when they probably have more pressing concerns to learn and care about? We only have so many hours in a day and so many days in a lifetime, while knowledge is practically infinite.
You could say that about anything. I limited my initial statement to educated folks, and presumably those who would like to be one. /history/democracy/milestones -> relatively important.
Hell, I would even go as far as to say the American Revolution is irrelevant even for most Americans because it has nothing of practical value. We (Americans) all know about it to varying degrees, but again that is due to growing up and being indoctrinated in it.