Assuming that "some writers write letters to their mothers" and "no one writes a letter to their mother expecting it will make them some money"[1], then it's not literally true, but we're splitting hairs. We're talking about hiring programmers based upon a portfolio of professional-quality work they've done in their spare time. How many writers would get a book contract based on a portfolio of their unpublished work?
[1] This requires more qualification. For instance, if one was a struggling writer who didn't make enough money from their writing but had a wealthy mother sending them money for their living expenses....
> How many writers would get a book contract based on a portfolio of their unpublished work?
Certainly not many, because how anyone could know they actually wrote something? But I was speaking about published but not paid for works. There is more than one way to publish your writings and many of them do not involve financial compensation. I know, because quite a few years ago I was publishing short novels and articles in a (real-world, made-of-paper!) magazine about pen&paper RPGs. I didn't earn a penny (and the magazine went out of business quickly), but I was published.
I wasn't the only one who submitted texts to the editors of said magazine. Mine were of poor quality, but there were a few authors that I was not surprised to find in the bookstores some time later. They got a book contract (I don't know, I'm guessing) from real publisher probably with less hassle than other debutants, probably because of what they published for free earlier. You can argue that they became writers only after they were paid to write a book, but I don't see this that way. Also, many of them continue to contribute they writings (mainly reviews, essays) to on-line magazines (about RPGs; sadly, there is no one such a magazine still being published on paper in my country) for free.
How is this different from publishing side-project on github and getting hired based on that? I really can't see the difference.
Either way, thanks for interesting discussion, I enjoyed it, especially footnote about writing a letter to one's mom :)
[1] This requires more qualification. For instance, if one was a struggling writer who didn't make enough money from their writing but had a wealthy mother sending them money for their living expenses....