Pretty sure Dick wrote LOOP. There was an ai working paper on the subject by him iirc too. Teitelman had left mit by the time I got there, though I later got to deal with DWIM (which seems to have infected web browsers and npm etc :-( ) at PARC. one great titlemanism was the addition of ] to Interlisp.
The basic idea comes actually from Interlisp and Warren Teitelman‘s ‚Conversational Lisp‘ and its FOR macro.
The main purpose of LOOP is to question ones assumption what is Lispy and what not. ;-)