IME, it's because a.) it requires one to first admit one doesn't understand something (and hubris prevents this in some people) and b.) learning something requi

IME, it's because a.) it requires one to first admit one doesn't understand something (and hubris prevents this in some people) and b.) learning something requires putting forth the mental effort to understand it. The same reason people don't like reading source code they didn't write: it's hard, and you have to try. And to a degree and in some contexts (particularly work/in a company), c.) under too much time pressure to take the time to understand. (I.e., too little time is available to them; the dysfunction is higher up the ladder…)