Yeah at least several years ago I had an explanation for this (though I’m not sure if it still applies). Basically, I think one reason for this weird type of interview is that it was an indirect way to bias towards young hires.

Young people have that energy and naïveté to do a lot of the grunt work. And most work at any established company is kind’ve grunt work. Anyways, just a random theory but nowadays it may be backfiring.