YAML sounded like a really great idea to me, until I started actually reading about it. It's a literal minefield.

Some parsers intentionally support subsets of the spec for this reason, and there's multiple specs (like 1.2 which dropped support for things like 'no' to mean false), but that also just means you need to be 100% certain your parser is set up correctly. It's just not worth the extra headache to me.