Peter Fisk observes...
Lisp is like “executable XML”. Much more powerful and flexible than Xaml.In the very early 1990s, Lisp was actually used to define at least one standard information exchange notation, EDIF: the Electronics Design Interchange Format.
The someone latched onto this overly complicated angle bracket element and non-bracketed attribute stuff.
Now we are getting back to sanity with JSON, in some ways even better than Lisp. It is almost as easy to parse and arguably more readable (e.g. easier to distinguish pure lists from property lists).