>>306487487
>at least some of that.
Well, there you go refuting yourself in your last sentence. "Some of that." 
Not all of that, not all the parts you think are important, but only some of it.
That very much allows for someone not to know Specific Meme #23489 from Board /xyz/. Maybe they know Meme #89213 and 30k other ones to autistic detail instead, some of which you or me certainly missed. Much like you can know a lot of detailed trivia about the historical usage of the term "weeaboo" but not know the trivium about its source.