Having an easy on the eyes markdown that is also easy to parse would be cool.

But YAML does these things:

https://ruudvanasseldonk.com/2023/01/11/the-yaml-document-from-hell

which are not excusable, for any reason.

YAML is good for files that have a very flexible structure or need to define a series of steps. Like github workflows or docker-compose files. For traditional config files with a more or less fixed structure, TOML is better I think