[maxfurman]

There is something about the language and/or community that leads folks to build their own X instead of collaborating on a common open-source version of X.

Perhaps the lisp learning curve is high enough to dissuade those who want to contribute to a project but don't yet know Clojure?

[ilkhan4]

I have a pet theory that it's because it's too easy to write code in. I think there needs to be just enough pain with a language or library that it becomes worthwhile to allow someone else to write X and just deal with it being imperfect if it still solves your problem.

[ballpark]

too easy and too fun.

Also, to anyone interested in this problem, look for the Worse is Better paper