Common Lisp has CLOS. I'm aware some purists don't think Scheme is a Lisp but, regardless of one's stance on this, there are most definitely other Lisps than Common Lisp.
Moreover, why not just say Scheme or Clojure when talking about Scheme or Clojure?
If ANSI C had been called ANSI Common C, would Java fans never cease to insist on calling Java a dialect of C?
There are more Lisps now than ever, so perhaps that was not as successful as was hoped.
> why not just say Scheme or Clojure when talking about Scheme or Clojure?
Why not just say "Common Lisp" when you mean Common Lisp, and "Lisp" when making true general statements that include other things that have always been considered Lisps? How are we to refer to Emacs Lisp without tying ourselves in knots if we refuse to say that "Lisp" includes it?