> A simplified subset of (HT|X)ML that uses only elements and no attributes is pretty much directyl equivalent to S-expressions, sure.

Add one more type, like a map, now you have attributes

  (fn btn ()
   (div
    {onClick (fn ())}
    "Click me"))

Have you ever tried parsing html in s-expression languages before?

For example, in elixir parsing html is this syntax: `{html_tag, attributes, children}`.

You indeed can include attributes in s expression

Every Lisp I know of has SXML either baked in, or as a library because it absolutely can represent the fullness of HTML...

    (parrot (@ (type "African Grey")) (name "Alfie"))

Becomes:

    <parrot type="African Grey"><name>Alfie</name></parrot>

https://www.gnu.org/software/guile/manual/html_node/SXML.htm...

Yes, (HT|X)ML have a semantic model that that can be represented in Lisp syntax, but so does everything else (well, every programming and data representation language, at least.) They don't do it with the same (or simple parallel) single simple syntactic fiundaton as Lisp, but with something more complex.

... I'd call that simple, without complex additions. You're not exactly requiring a parser, here.