As others have noted, the article is based on a study that only looked at a small subject of OSS projects, so it's not very solid. But the results fit with many commenters' perceptions. It's surprising that so little is known about the dynamics of how OSS gets written, given how crucially important it is to the global economy these days.

(Even) more broadly; I wonder if a similar system will wind up dominating in some fields of science. There's been a bunch of cases where prominent research papers in AI or biomedicine have been published by entirely for-profit companies; one supposes they benefit in the same fashion that more traditional software companies benefit from publishing open source work, namely by building a reputation and cultivating a larger ecosystem around their expertise.