"Employers overvalue experience"
Only at hiring time. One of the execs reads a journalist article in a trade rag about any random fad and "we" need to have it implemented yesterday. Which is not a problem because successful employees are really good at OTJ training and learn by experimentation. Unfortunately no one has told HR that, and they think they're hiring for tax audit avoidance accountants in the most conservative and uncreative criteria possible.
The ideal candidate has 20 years of experience in a field 10 years old (that only takes 6 weeks to learn of course), in other words focused entirely on the past. The ideal employee on the other hand is an expert at learning "6 week" technologies and making them produce once they're hired. There's going to be friction and failure and massive wastes of money.
There is also the extremely low social status issue. It would be possible to micro-specify (nano-specify?) any management or executive job, but they're not going to put up with it, as an industry, so instead we get "good judgment" type of hiring criteria. The reason why programmers have incredibly low social status is the oversupply (nationwide, anyway) requires them to be talked down to or replaced by someone who will tolerate being talked down to. The extremely low social status permeates the rest of the field too, call center like work environments, crazy disrespectful deadlines, poor management techniques (most modern fads, really), so its not going to be as simple as some sort of union saying "no" to disrespectful job advertisements.