This is a little-appreciated benefit of using Common Lisp: the language is both standardised and stable, so a library from 2000 is very nearly as likely to run on an implementation today as it was then, or as another library is now.
I do wish that there'd been a newer standardisation effort since, for a couple of reason, but it's really, really nice that the people haven't had to waste effort updating working code to deal with language changes.
Agreed, that's one of the more important advantages of Common Lisp in my book. But the reason it works so well is that the standardized version was based on plenty of experience and experimentation, and that it's powerful enough to be extended from user code; same goes for C to some extent.
I do wish that there'd been a newer standardisation effort since, for a couple of reason, but it's really, really nice that the people haven't had to waste effort updating working code to deal with language changes.