Companies advertise they're hiring. Like they advertise that they're profitable, make the best products, and are better than their competition. That doesn't mean it's true. Many positions are "nice to have", so they will stay there until they get someone with far more experience on paper than they actually need - someone willing to get paid less of course.
People lie, especially companies. That's the nature of the market. Even if we had 5x the devs than employers, employers would still say otherwise. This is because more competition between applicants means you can pay people less.
Infact even during the dotcom boom my sister actually got a degree in "web development", and nobody wanted anything to do with her. I don't know who comes out with these lies about "high demand" employment but so far all I've seen is confirmation bias by those already employed - ignoring all the rest of the people who can't get anywhere, leave it behind, and go work at something else.
