> YAML is fine for what it is: a markup language.

Pardon my pedantry, but the meaning of YAML's name was changed from the original “Yet Another Markup Language” to “YAML Ain't Markup Language” in a 2002 draft spec because YAML is, in fact, not a markup language :)

Compare:

https://yaml.org/spec/history/2001-12-10.html

https://yaml.org/spec/history/2002-04-07.html