I think the biggest reason is demographic in nature: The rapidly expanding population of professional programmers means that programmers are regularly building

I think the biggest reason is demographic in nature: The rapidly expanding population of professional programmers means that programmers are regularly building their skills on third-hand advice while simultaneously encountering situations nobody they know has seen. In such a climate, they aren't really competing for the job on the basis of merit, so much as they are posturing that they are a good candidate - because they learned that that's what one does to get work and protect their family. And there is so little expertise around that nobody can call them out. When they get hired, the posturing turns into gatekeeping in short order. They aren't curious about the work, they just want to keep the position. When you fill the ranks with uncurious individuals you get stagnation, because nobody is pushing them forward. In other professions the process of education and certification cuts most of these people out early on, which comes with its own downsides but does impose some minimum standard of capability which they may go on to use or misuse. But the problem in programming is that the tools of programming address a multitude of problem domains, outstripping what could be reasonably certified - that's why the profession has gotten so big, so quickly. It's all research, all the time - independent, unverified, unscientific research. In response to this we've ended up with the whiteboard coding interview, which basically aims to do the task of certification within the span of a few hours. It's not very good at that - these interviews are run in an inconsistent and often unprofessional manner too.