This is a niche skill industry. You can't be everywhere, if you intend to be good, and if you're good at something, you are probably not going to be good at completely different things. And someone very good at a small niche is almost always more valuable than someone who is kind-of-good at a number of things.

Startups may need "eager, polyglot programmers who are willing to get their hands dirty, learn on the job", etc., but by virtue of that they're eliminated from the market for many of the higher-skilled, specialized people.