YAML claims to not be markup, but it clearly is a markup for data (significant whitespace/indentation, etc). When I want to do markup, I use Markdown.

When I want to data serialization, I use JSON. It's incredibly easy to strip comments (and whitespace, for that matter) from extended JSON before transmitting and/or parsing. I wrote `JSON.minify(..)` for that years ago, and it's literally never been a problem for me since.