This isn't different though. This article was written as "How to get into ML" and is basically selling the idea that getting into ML requires (or is aided by) doing some independent open source work to bulk up a profile.

A very competent developer who is interested in doing some ML work may have just recently read this article and gotten to work on an ML project because he feels that not doing so will hurt his chances of getting a job.

As a note, I have no idea what the right solution to this problem is, it is good to confirm candidate's knowledge (I prefer creative ways similar to the parent) and part of that knowledge certainly can include open source work, but going down this road too much leads to people feeling obligated to make open source work to put on their resume and even to people faking open source work to try and land a job.