> What is absolutely baffling to me is that companies assign coding tests as a pre-qualifier for the usual whiteboard interview despite the coding test being a far more adequate measure of the abilities of an engineer.

A coding test doesn't tell you how well a candidate can collaborate. Can you toss them an idea, and have them successfully expand it and put it to use? Can you give them a couple of half ideas, and they expand them to full ideas? Would they be able to work together with you? Can they understand you? Can you uderstand them?

Those are all vital components to success, and you can't see those answers from a test. But white boarding is excellent for answering all those questions.

A quick word about hoop jumping. Being willing to jump through hoops means you're willing to cooperate and go the extra mile, and that you want to work at the company in question. This is a useful filter for the employer. They might lose some of the least patient and dedicated engineers (and perhaps some of the most talented) developers in the process.