Why would someone have no way to corroborate their industry experience? I can show you thousands of lines of code I wrote on the job. Even with an NDA there are ways to show your achievements.
Anyway, I am not saying side projects don't get peoppe jobs, that was never my argument. My argument is that talented developers don't always have side projects all the time. Some of them are already highly skilled and work in challenging enough environments that they continue to learn anyway. The grandparents argument was that anyone without side projects is suspect, that is demonstrably false.