This seems like the real takeaway. An experienced programmer should have some evidence that they do good work, whether that's products or OSS commits or something else altogether (e.g. someone in security who can't talk about their work details but does papers and conferences). Good hiring means being able to adapt to where a candidate has spent their effort.
...if it exists at all anymore!
In many cases, the examples of my work have evaporated. At one point, I could point to certain websites I had a hand in developing as an employee for past employers - but those sites have since changed, moved on to other software development companies (one of my past employers folded and those clients went to other agencies for web dev work). I can still list I worked on such work, but I have no code or other proof.
So my github (and interview results/conversations/etc) are where its at - and ultimately, that's where its always been (I've been doing software development work since the early 90s, when I was coding on VT100 terminals over a serial link).
As a long-time developer from the embedded world, I'll add the same sentiment. I've written 25 years of code that's 100% proprietary to my employers and my customers.
I've never touched Github and, at this point in my career, it looks like I never will.
Granted, I have a product portfolio that I can point to instead. The rubber has to meet the road sometime so yeah, in the open-source world that's the only visibility you have so you go with it.