I have also worked with many companies that are pretty huge, cash positive, exploding growth, and with very complex software as their product. They made a rule of not hiring using DS&A after accidentaly coming across a tier-3 college student with no knowledge of DSA and still doing pretty well (and he didn't jump ships too), so then changed their strategy to: only test them for what you need from them. I will give it to Google and FB that their technical scale is much much larger than that company, so they might demand engineers who can understand that.