This is good one!) The insight were there for s long time - DSLs were popularized in SICP and AoMOP, and CL's looping expressions and SETF/GETF are the most famous, but PG is good at concise writing and he walked his talk with the Arc language.)
Don't get me wrong, I liked On Lisp a lot. I just think it's important to recognize that much of it is a distillation of pre-existing understandings and traditions.
Yes, it's well known that - in some sense - there were no Lisp programmers until 1993.