People are generally looking to hire themselves. So if someone memorized the amazon coding question handbook, they expect that anyone applying to work at MidCo have done the same. Same with people who consider themselves “enthusiasts”. At my old job, it reached the point that we had to schedule interviews around one of the major project leads going on travel because, otherwise, he would be insanely obnoxious as he insisted they should know everything about whatever C++ standard proposal he read last night.
And that obviously also has issues regarding diversity since a lot of the same “I am the best person so everyone should be like me” mentality folk tend to want to hire people with a similar background to them…