The reasons tend to vary by region, but they still often come down to people playing games with job postings to try to get someone to fill a role that is bigger

The reasons tend to vary by region, but they still often come down to people playing games with job postings to try to get someone to fill a role that is bigger than what they are willing to pay for. I've had two employers give me a job title that didn't reflect the work I was doing, and allowed them to pay me less than they would with the correct title. Job postings in my region tend to either have a pay range that looks like it belongs on a posting which requires 5 fewer years of experience, or they put something into the requirements as a "must-have" skill that would normally bump the rate. Another part of the problem is that much of the educational system has put itself into the position of job training instead of educating when it comes to development and systems/network administration. It is often difficult or impossible to find a good curriculums for administration. Computer Science curriculums often choose languages based on the insistence of employers that those languages are necessary in the job market (though the average lifespan of some languages in the job market is less than the average student spends getting a BS in Computer Science). Meanwhile, employers often mistake experience with a given language as a higher qualifier than overall development experience and ability to learn and adapt what you have learned in one language to working in another. This seems like it should be especially relevant in web development, since full-stack developers have to be familiar with front- and back-end languages, markup, stylesheets, and often at least a little SQL. Finally, there's high turn-over and the ever-present revolving door positions. I've met far too many people who go back to school to either get their MBA and move into management or to get a degree in something else just to get out of the field completely. People get stressed out, treated terribly, and often feel like they have to completely re-learn their job every few years to maintain basic skills. After 5 or 10 years they may reach the salary cap for their job title, and they may have no opportunities for upward movement in a technical position. A new person might come on board to do nearly the same job, sometimes with the same (or more) pay, while being less qualified and less capable. All of these things still trend in one direction, though: employers undervalue an applicant's overall experience while over-emphasizing a combination of skills which isn't often found in one person, all because they not only aren't willing to pay the going rate, but don't even want to hire enough people to do the job.