There's a couple things this author didn't mention that is important when you analyze the software developer labor market.

First off, the overwhelming majority of developers are senior developers. If it takes X years to transition from a junior to a senior, then that means every single developer is a senior, except for those who started within the last X years. I think a lot of articles like this make the mistake of assuming that senior developers make up a small percentage of the entire developer population.

Another thing to keep in mind is that the average age of a software developer is very young. The very first generation of developers are only now starting tor retire and leave behind job openings. Other industries, for example doctors, don't have this problem. There is a rate of doctors who graduate medical school, and a rate of doctors who retire, and that rate differential determines the ease of getting hired right after medical school. The retirement rate of developers is extremely small. In 2018 I did an onsite interview at Google, and I was blown away by how young everybody was. I was 35 at the time, but it seemed the average age of people that I saw there seemed to be about 22 years old. Eventually, after a decade or so, the retirement rate will increase, and job openings for juniors will return, but it's still a long ways off.

One more thing. My personal experience is that it was easier to land a job as a junior developer back in 2010-2012 than it is to land a job today in 2020 now that I have 10 years of professional experience. It always bothers me to see people post about how its so easy to get a job if you're a senior developer, because I just don't see it. Its as hard today as it's ever been. Year after year I experience more difficulty finding a job than ever before. Every single interview I've done in my entire career since becoming a "senior" (sometime around 5 years into my career), never once have I felt like I'm being treated like I'm a valuable resource. For instance, with my last job hunting stint, I made it a policy to turn down all interviews where I was asked to do either a whiteboard problem, or a take home project. Without exception, every single company said "fine, bye". If senior developers are such a rare resource, you'd think at least one company would try to negotiate with me and try to make it work out, but no. Every single company was fine with letting me go after refusing to do the whiteboard/take-home. Even in 2010 when I was first starting out, I felt more respect coming from companies during the interview process.

I don't believe in this idea that there is a huge demand for senior developers, and extreme low demand for junior developers. It only makes sense that both would track the same level of demand. There is no fundamental difference between a junior developer and a senior developer. They are both developers. With the senior, you get a little bit more productivity, but the junior gives you productivity too. I would believe it if seniors had good demand, and juniors slight less, but still good demand. Or Senior developers low demand, and junior slightly worse demand. But I don't believe senior is high demand, and junior is low demand. That just doesn't make sense.