I think the suggestion was just phrased a little awkwardly.
Lisp is so easy to program that it is commonplace to reinvent builtins -- they are as easy to write as they are to find (especially in an, er, mildly documented language).
I went proactive on reinvention thang and invited people to let me know of things I had reinvented. Somewhat tangentially, I also make an effort to use things like [... _ ...] and func.arg to give pg's ideas a fair test and so my Arc code can help other noobs get up to speed on the language. If I stay as close as I can to my preferred Common Lisp, like someone writing C in Common Lisp neither I nor anyone else gets a feel for Arc. But I digress.
