This was the one that really stood out to me. MOOCs, bootcamps etc are wildly popular now and vary massively in quality. It's very easy for candidates to look good on paper but not actually know the technical side as well as they should. More importantly, software engineering is one of the few jobs where you can get a (somewhat) quantitative measure on prospective performance so it's natural to take advantage of that.

I'm not saying that All Coding Tests Are Good, but they do provide a modicum of certainty in a very uncertain environment.