I've been a professional programmer since 1978 and the article seems 'off-beam' to me. He thinks that because programmer was harder 30 years ago, that would be there was a higher barrier to entry and therefore only really good programmers would get programming jobs. That idea is just completely wrong. There were the same number of people who could program as opposed to those who weren't very good as there are today.
Most programming goes on in your head in my opinion, and it is very much the same today as it was in the 1970s. You need to be able to run programs in your head if you are writing a COBOL program on coding sheets, that are sent away to be turned into a deck of punched cards, and once the cards are punched you can get them compiled into a program at most twice a day. If you want to be a really good programmer today, you need to be able to visualize what you are working on in your head. To me that is the ability that separates average programmers from really good ones - a good programmer doesn't need a computer to program, although having one is obviously handy..
For me there have been two big changes in how you conduct a programming career. The first was the introduction of personal computers that were cheap enough for a programmer to buy and use them to learn new programming skills in their spare time. The second big change was Free Software where you could publish your own code, and collaborate with people over the internet. I bought a Macintosh in 1984 and used it to learn Pascal with MacPascal. Then I got a programming job using Pascal. More recently I did a Ruby/C++ Free Software project and got jobs as a Ruby programmer and as a C++ programmer as a result.
Only really good programmers can write Free Software and handle open reviews of their work, and so if the article was about 'better self selection of programmers', then people who write software in public today are way better than the average programmer of 30 years ago. The very best programmers of today are much the same as the very best programmers in the 1970s, it is just that they are easier to find today. That is assuming you think people like Linus Torvalds or Rails DHH are examples of the best programmers in the 21st century.