Emacs Lisp is deeply embedded everywhere in Emacs. For example, a character can carry some 'display' properties that contain Lisp code, and the display engine will actually run the code [1]. The same cannot be said for Web engines. Of course, the usefulness of this is quite debatable -- the display of Web elements can be managed by CSS just fine.
juxtapose|2 years ago
[1] https://www.gnu.org/software/emacs/manual/html_node/elisp/Di...