Your snarky question is so far drawing a lot of snarky responses.

However, the implied question here is absolutely valid: Why write your own flat-file format parser from scratch, when there's a multitude of battle-tested third-party libraries already in existence?

I mean, if you're writing something very specialized or proprietary, that's one thing. But if you're simply proposing a generalized tree shape that looks like YAML, then why not indeed use YAML? I know it's tricky to write a YAML parser... but so what, why would you? There are already a ton of great ones.