Greenspun's rule refers specifically to Common Lisp ("... of half of Common Lisp.") and there's no way that "half of Common Lisp", even with a healthy dose of h

Greenspun's rule refers specifically to Common Lisp ("... of half of Common Lisp.") and there's no way that "half of Common Lisp", even with a healthy dose of hyperbole, can refer to the feature-intersection of all popularly-implemented Lisps, nor to anything "very pure".