I’ve looked a bit at the original reddit code (it is/was published on GitHub) it does a lot of things in unusual ways for a lisp project and I’m not too surprised that they abandoned it: I’m pretty sure that if they had rewritten it in lisp, taking advantage of what they learned, the second version would have worked as well as the Python rewrite.

Also, quicklisp didn’t exist/wasn’t as widely used then: I’ve done all sorts of Lisp projects now and never had serious issues finding good libraries for standard web development tasks.