One hypothesis I've heard is that companies have found that the kinds of questions that get asked in programming interviews can serve as a decent proxy for IQ t

One hypothesis I've heard is that companies have found that the kinds of questions that get asked in programming interviews can serve as a decent proxy for IQ tests (which are effectively illegal for hiring purposes), if they choose the right questions. So even if these questions aren't related to the day-to-day work programmers do at the company, it could give them a legal way to filter for intelligence. I say that it could because I think they'd have to select the questions fairly carefully to ensure they're achieving the intended result, and then compare the success of the candidates hired via those questions vs. the success of those hired via work samples or different types of interview questions.