As a data format, yaml is extremely complicated and it has many footguns. In this post I explain some of those pitfalls by means of an example, and I suggest a few simpler and safer yaml alternatives.
I can kind of understand it after having to work with an XML file where users encoded data into comments for no good reason. But yeah, it does make JSON awkward for lots of potential use-cases.
In an ideal world, yes. In a locked down world where you have access only to 1/4 the codebase or your job is more ontology-focused, all you have access to might be the JSON. Leaving a comment or two about why a particular value or hierarchy is as it is is sometimes more clear than writing up a seperate README that no one will read