[recursivecaveat]

I was under that impression as well, but it was added as an implementation in 3.6 (https://bugs.python.org/issue27350), so I don't know that too many people would have become dependent on it before it was official in 3.7: https://docs.python.org/3/whatsnew/3.7.html

I think the "how/why" thing is just the automatic title de-clickbait-ifer going a little haywire?