> Well, it was. Specifically, Common Lisp was. But that language's standard was etched in stone in 1994 whereas languages like Python (where most deep learning user-facing code is done) continue to evolve.

This is an apples to oranges comparison. The Common Lisp standard hasn't been updated since 1994. The Python standard has not been written at all yet. Lisp and Python implementations both continue to evolve and be released.