Microsoft is to pay $7.5bn for a business that makes it easy for software developers to collaborate with each other, but doesn’t itself actually make any money. The purchase of GitHub (to be paid for in Microsoft shares) may look from the outside like just another piece of lunatic Silicon Valley economics but is in fact an important development in the slow, tectonic collision of the libertarian ideals of late 20th-century California with reality. GitHub and its users were once the sworn enemies of Microsoft and everything it represented. Bill Gates’s firm built software for profit and tried with every means at its power to ensure that no one used anything else. “A computer on every desk and in every home, running Microsoft software” was its aim, and it went a long way to succeeding in this extraordinary ambition. Most of us now use the computers in our pockets (known for historical reasons as “phones”) as much as those on our desks or laps, but it is still true that anything that won’t fit in a pocket will likely be running some kind of Microsoft software.

GitHub, by contrast, grew out of the free software movement, which had similar global ambitions to Microsoft. The confused ideology behind it, a mixture of Rousseau with Ayn Rand, held both that humans are naturally good and that selfishness works out for the best. Thus, if only coders would write and give away the code they were interested in, the results would solve everyone else’s problems. This was also astonishingly successful. The internet now depends on free software.

Possibly the most important of all the free software projects is the Linux operating system, which is built and maintained by programmers all over the world. Linus Torvalds, who started and still runs the Linux project, built a piece of software called Git to impose order on this potential anarchy. GitHub, in turn, is a place where people and companies can store copies of the files managed with Git and anyone in the world can find them easily; 25 million people now use it.

But the belief that everyone coding would solve anyone’s problems has been shown up as completely ludicrous. If anything, computer literacy has declined over the generations as computers have got easier to use. In the heyday of Microsoft, almost everyone knew some tricks to make a computer do what it should, because almost everyone had to if they wanted to get anything done. But hardly anyone today has the first idea of programming a mobile phone. They just work. That’s progress, but not in the direction some idealists expected. Significant open source software is now produced almost entirely by giant commercial companies. It solves their problems but could be said to multiply ours. Huge cultural and political changes are presented as technological inevitabilities. They are not. The value of GitHub lies not in the open-source software it hosts, which anyone could copy, but in the trust reposed in it by users. It is culture, not code, that’s worth those billions of dollars.

• This article was amended on 8 June 2018 to clarify that GitHub hosts open-source software, but it is not open-source software itself as an earlier version implied.