MathB.in, a simple pastebin for mathematical snippets, went in the opposite direction. It was first written in PHP and then later rewritten in Common Lisp. See https://susam.net/blog/mathbin-turns-ten.html for the full story.
I would argue that for such a small website (in the sense of both codebase size and traffic), which language is used does not matter, and is almost purely a personal preference.
I checked out MathB.in. Neat stuff!! I've started and stopped with the Lisp/Schema family several times. When other languages frustrate me, I go back to lisp for some therapy.