I mostly agree but YAML sounds like a serialization format and not configuration format to me.
I think a large amount programmers don't realize nor respect the history. Early Java proliferation was during the late 90s and early 2000 on-premise enterprise software. Customers required extreme customization but not all of them wanted to actually crack open and edit files.
The customers wanted to use tools and XML works great for bidirectionally editing not to mention there were shit loads of XML editing tools at the time (XML Spy).
> XML on the other hand is relatively easy to parse, but has a complex data model that maps well just to a DOM. For anything but markup text, you do not have a direct mapping to/from XML.
One of the reasons Java originally pushed XML is the support for it so good (tooling and editors). Java actually has great support for mapping XML to objects (JAXB).
YAML has more complexity in syntax, but a data model that fits to data structures in programming languages (records/maps, arrays/lists, integers, floats, boolean, bytes, strings). As long as you do not implement a YAML parser yourself (why would you do that?) you should have easy times with YAML.
XML on the other hand is relatively easy to parse, but has a complex data model that maps well just to a DOM. For anything but markup text, you do not have a direct mapping to/from XML.
> Developers write hundreds of lines of XML all the time... its called HTML
There it makes sense, because it is marked up text you are writing and it is the right tool for the job.