I mean, that story's about to be 15 years old, but I take your point. When I'm asked to prototype something that seems to pose a real danger of the next step b

I mean, that story's about to be 15 years old, but I take your point. When I'm asked to prototype something that seems to pose a real danger of the next step being "okay let's deploy this", I do it in Emacs with org-babel. That's more than enough of a programming environment to validate an idea, and like a notebook each code block's results become part of the document, so it's very observable - but thanks in no small part to Emacs's reputation as alien space magic for weirdos, nobody's ever been mad enough to consider trying to jam it in production as-is.