I don't think that's necessarily true. Some of the best programmers are abysmal interviewees. So I would suggest that there are a ton of briliant programmers out there with jobs that are well below their level.
If an employer overlooks good code and instead places more emphasis on an amorphous process like an interview which has plenty of false-negatives and positives , then i would argue against working for such an employer.
I know a few people whom I consider amazing programmers, but that I'd never hire and feel very dubious to have as colleagues due to their personality and how they act. There are very few jobs (if any) where all that counts is the quality of what you put up on github.
Fair enough, but i never said hire programmers based "only" on their code in github.
The assumption here is that certain programmers do not do "technical" interviews well and they can therefore point to their code as proof of their technical competency. If their personality is broken well - that's a completely different problem and i don't know the solution to it.
Either way, i think this particular strain of discussion is in someways orthogonal to the main point of the article.