My read of the article was quite different. Namely, "Imagine you had to shave a yak. There would be a lot of things involved in getting that done, many of which you don't know ahead of time."
Ultimately the same underlying meaning, but quite a different illustrative scenario.
Yes I've heard this too, but I've also heard both.
While writing this I found a lot of opposing definitions (as mentioned with bus factor). I've also heard "Don't shave the yak!" as part of the definition you gave for yak shaving.
Thanks for the feedback! I'll incorporate this too to make it more complete.
Ultimately the same underlying meaning, but quite a different illustrative scenario.