I think I'm pretty safe saying there are a ton. Every Lisp hacker has their own.

Actually, "library" is probably the wrong word for reused Lisp code. A library is a public thing, an institution---and all that goes with it: slow to change, must be easy to understand, etc.

Instead of libraries, Lisp hackers have private collections. Like a messy desk, they are often supremely useful once you get the hang of it, but are inscrutable to others. Not exactly the best characteristics to get popular on github.

I don't know where you're coming up with this impression at all. Clojure has Leiningen and Maven, Racket has PLaneT, CL has QuickLisp, etc. In my experience Lispers do not waste time solving solved problems.

Certainly Github does not in anyway support your claim: https://github.com/languages/Clojure

popularity, culture and ease of sharing libraries(ex. cpan) for one.

But also its not that its great for writing libraries but that its great for writing libraries that extend the language.

I think that Zach Beane is doing a stupendous job with quicklisp. Of course it's nowhere near CPAN at this stage, but it's a tremendous step forward compared to, say, plain asdf-install.