> Open source contributors self-select.

You are looking only at the last step into becoming a FOSS contributor. There are other selection filters you have missed, but which are touched on in the essay.

The article mentions "the vast majority of open source contributors are either volunteers or work for sponsoring organizations." I believe that is correct.

Those who work for sponsoring organizations aren't quite "self-selected", in that their employer is also involved, if only to grant copyright permission. I wouldn't say that all of the Google staff working on the open-source part of Chrome are self-selected open source contributors. Would you?

And don't forget the article mentions a Fortune analysis that "the world’s biggest companies, who are the frequent sponsors of high-profile OSS projects, are still lagging behind in diverse hires." That's a selection filter right there.

Even if all FOSS contributors are self-selected, there are clearly systemic biases in who is able to make a decision.

Consider the mentioned "unpaid care work", which includes raising children and taking care of the elderly. Many societies regard this as a woman's responsibility, so even if two people have to decide to spend their volunteer time working on open source vs. doing unpaid care work, a man in those cultures may find it easier to "self-select" open source development than a woman might.

> If you think there should be more people sending patches or running FOSS projects, bring them

Someone working two jobs to support a family has little free time for open source development. Someone working part-time at a job and full-time child minding also has little free time. OTOH, someone with money can have a job with the evenings off, can pay for a babysitter, can order food instead of cooking, etc.

As a result, poor people are underrepresented in open source software development if only because of the lack of available free time.

Historic racism in the US contributes to the modern correlation between wealth and the social construct of "race". Blacks, for example, are more likely to be poor, and therefore less likely to be in a position to be able to "self-select" in the first place.

Personally, I see Universal Basic Income as a way to get a lot of good open source developers, by increasing the number of people who are able to volunteer.

> I don't know of any FOSS project who asks, or cares, about race or sex or anything else except code

Have you missed the last 10 years of discussions about FOSS projects that have actively removed the use of "master/slave"? That sure sounds like FOSS projects which (at least claim to) care about race.

Here too you are looking only the end point of the process - someone who contributes to a FOSS project. Those who have removed "master/slave" argue that such terms may inhibit people from becoming a FOSS contributor in the first place.

Similarly, a FOSS project with a Discord project discussion channel where the developers regular post pictures of sexy women might disproportionately inhibit contributions from women.

Even if they are completely wrong, my point is that there are many selection filters beyond "does a project accept or reject code based on the contributors race, sex, etc."