I think you are being a little shortsighted. You may mean it doesn't get you jobs in the specific area that employs most of the people you share online/offline time with.
I'de bet most of the guys that programmed the operating system you were running when writing that post got paid for they job. The same goes for people developing compilers or VMs, like, you know, the one Python/PHP runs on... and don't get me started on database servers.
That is definitely true. But how many compiler and VM jobs are there? How many web monkey jobs are there? It's like automotive engineers, as opposed to mechanics and drivers.
Now, I realize that we're being trained as automotive engineers, but most of us get jobs driving. I think the blog post's advice is much more useful for that.
Good analogy, but then developers are more mechanics than drivers.
You can use your cool and deep automotive engineering knowledge to "do mechanics", but most of the time is not efficient cost/benefit wise. Most of the time it's more important to get the thing running in order to start the business.
I'de bet most of the guys that programmed the operating system you were running when writing that post got paid for they job. The same goes for people developing compilers or VMs, like, you know, the one Python/PHP runs on... and don't get me started on database servers.