I could not live off my website being free, I have a day job.
And as the author says, open source advocates tend to be more libertarian.
And also as the author said, using 'socialism' will make people cringe. Yes, because the author is trying very hard to find 'digital' socialism.
Socialism and Communism are specifically to do with shared ownership and control of capital resources. Feely choosing to give things away isn't socialism, or inherently anti-capitalist. It's simply the exercise of one of the freedoms of private ownership of one's goods or labour - the freedom to share it or give it away.
Yes, but know-how of all sorts - including both the freely-available content of sites such as Wikipedia and the institutional frameworks that are themselves embedded in the computer code of e.g. MediaWiki, Mastodon, PixelFed and PeerTube - is a form of capital, too. In a way, the article is not exactly wrong; it's just that this instance of socialism - along with a few others, such as socialization of basic, monopolized "platforms" on a rigorously neutral basis - postal services, roads, railways, power-grids etc. etc. - is the only one that can possibly work as part of a wealth-creating society. "Communal ... shared spaces" are capital in the "capitalist" sense, as much as a privately-owned factory is.
Political and economic socialism is predicated on the principle that individual ownership is immoral, because resources should belong to society. This is why socialists are against the individual, or even collective ownership of companies by shareholders because that's still private ownership. For them the sole legitimate owner is 'society' as a whole, which in practice means the state.
That's what genuine socialists believe in and campaign for, which would of course threaten the freedom of individuals to build something like Wikipedia. That's because they would not have individual ownership of the capital resources contributed towards it. The decision about allocating those resources would reside with the state, not individuals as free agents. Paradoxically, universal collective ownership dramatically limits freedom to organise collectively without state sponsorship. That's why you see communist and socialist countries cracking down on grass roots movements. They challenge the legitimacy of the state.
(Monopoly platforms are in kind of an intermediate position where what we want to avoid is simply for "the decision to allocate these resources" to be subject to the sorts of favoritism, opportunistic behavior and inefficiency that tend to come with monopolized private ownership. In practice, this is a weird case where public ownership turns out to work quite well; especially if the monopolization can be efficiently kept to a very local level, so that users are still incented to "vote with their feet" for the very best provider. All in all, it's not that different from capitalistic provision while avoiding some really obvious pitfalls of entirely-private models.)
Capitalism has provided a structure to create and sustain such services, while socialism fails to do so, or even follow in it's tracks. Buy why so? It's one of the fascinating characteristics of actual socialism that it's universalist ideals turn, when faced with the problem of practical implementation, into a centralising and therefore monopolising force. That applies to information just as much as capital, because ultimately all individual freedoms threaten a centralised authority that claims sole legitimacy to speak for society.