Things like age, class, education and educational institution, willingness to work long hours doing something you hate for a goal you don't care about except that it feeds and houses you.

Line engineers running interviews have stopped having any say in the corporate policies of tech firms years ago. They are cogs, not rockstars.

You are right, this definition does come from some person with some set of motivations, but that person is some mid/high-level manager who probably hasn't ever written a line of code in their life.

It's just tradition for the sake of tradition. When cargo cult practice becomes industry culture. Like a much milder version of why medical residents are put through extreme sleepless wringers just because William Halsted was a cocaine addict.