Earlier quoted context omitted.
> No competitive free implementation existed able to take a leading position and bootstrap the ecosystem, like gcc, cpython, perl and javac did for their respective language ecosystems. it was never a goal in the Lisp community to develop a single unified or leading implementation. This has nothing to do with 'free software' or not.
"it was never a goal in the Lisp community to develop a single unified or leading implementation" ...and that's one reason it hasn't ever achieved critical mass: it's so easy to write software that only works on one implementation that the various CLs effectively compete with each other on the same level that each is competing with other rapid development languages. It wasn't CL vs Python vs PHP, but instead CMUCL vs…
It seems to me that there are plenty of more popular languages with a similar glut of implementations: there are multiple JVM vendors, multiple implementations of Java (Sun/Oracle and now Dalvik, ...), many C and C++ compilers, etc...
This is total speculation, but it is perhaps because things like threads and networking were not part of the Common Lisp standard that there are fragmentation issues that impeded adoption? Or do you still think that canonical implementation vs language standard is that much better, in almost all cases?