Coding interviews make sense for great companies like FB and Google. Such companies receive probably tens of thousands of applications every week, and all the candidates who can get an onsite interview have impressive resumes. How do they pick the best and brightest from the best and brightest? Code interview at least sets a higher bar for minimum requirements for two types of candidates: - If a candidate is a genius, the candidate can solve those interview questions easily - If a candidate is not a genius but is truly passionate about CS, the candidate should have read or practiced enough to solve the interview questions too.

Either way, the candidates who pass coding interviews meet the minimum hiring bar.

And don't forget the historical context when Microsoft popularized brain teasers and algorithmic puzzles in its haydays. In the 80s and 90s, there were few interview prep books. There was no leetcode or any other pre site. Those so called teasers are cleverly disguised math puzzles. Remember the questions about pirates dividing up gold coins? Classic math problem. Remember the one that asks how many unfaithful husbands there are in an island? Putnam question solvable by mathematical induction. Similarly, the so-called algorithmic puzzles came from classic CS books or from real projects. Those who can solve the puzzles are either super smart or super geeky. Either way, they were likely to be great hires for Microsoft.