Great post! Love the various resources you brought together. This is definitely a tricky problem. Just thought I'd share some thoughts that came to me as I read it.
I was fortunate that when I started getting into web development, there was no whiteboard or test. Places were so desperate that showing any real ability was enough. All I brought was an app I'd built on my spare time. I had no formal schooling or formal experience. The .com boom days were unique and I was extremely fortunate. Had I been starting out today, my experience would have been very different and would certainly have required much more of me just to break into the industry.
I think you touch on some important points in that there is often too much focus on specific skillsets rather than overall fit. There seems to be too much emphasis on "hit the ground running" and very little effort to train and develop people. When I've had the opportunity to conduct interviews, I was often less interested in what specific language you knew or testing you on how deep your language-specific or computer science knowledge was than on finding out about your willingness and eagerness to learn. Language, framework and other specific skills can be taught, but you need someone who wants to learn. Companies need to learn to be patient and develop talent - I believe it pays off in the long run.
I'd also say that I have worked with all types. For example, some people were not most brilliant coders, but they were incredibly productive and didn't mind doing the mundane jobs that needed to be done, but that the "top 5%" coder would frown on doing because it felt beneath them. They played a critical role in the team regardless. My point here is, I also wonder if we often focus so intently on the pieces of the center pieces of the puzzle and forget the pieces around the edge that make the picture complete.
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