I can teach most people (including non-programmers) enough of a subset of yaml for them to edit/create working config files (for a particular app) in a text edi

I can teach most people (including non-programmers) enough of a subset of yaml for them to edit/create working config files (for a particular app) in a text editor by themselves. You cannot do that with XML If you're only reading and writing the files via a library, then XML is probably better.