[abrahamsen]

Does anyone really use all of Common Lisp?

I'd say the justification for all of the large languages (like C++ and Common Lisp) is the same. You may not need all of it, but the features you do need will at least be standardized, compared to using a small language with ad-hoc extensions to achieve the same.

[ I here include the standard library as part of the language, for languages with extensive meta-programming support like C++ and Common Lisp, it makes little sense to distinguish. ]