I chewed on the tasty food for thought of the blog series by Ramin Honary @ramin_hal9001 on how Emacs fulfills the Unix philosophy. If a Lisp system is extensible, customizable, and self-documenting by design I'd say it's an application platform, or pretty close.
https://tilde.town/~ramin_hal9001/articles/emacs-fulfills-the-unix-philosophy.html
Ramin, @sacha Sacha Chua, and @screwtape will elaborate on this in an upcoming episode of the Lispy Gopher show. Full context: