In what sense is iterate a fad that was gone? I see 1161 systems in Quicklisp (out of 5499 total) that transitively depend on iterate; so about a fifth of the open-source ecosystem.
For what it's worth, I quit using it since it broke if you ever used the CL function `count` inside an iterate construct. Reportedly it was fixed, but it's still failing to work correctly using the Quicklisp version (just installed CL on and setup QL since it's a new laptop, so it shouldn't be pulling an old version). It was fun for a while, but having to remember "Oh yeah, don't use count" every time I reached for it for something natural was annoying and not worth bothering with.
Methodology (yes, I could've stayed in Lisp, but I started by awking systems.txt...):
(with-open-file (*standard-output* #p"deps.txt" :direction :output)
(iter
(for system in (ql:provided-systems t))
(for name = (ql::name system))
(format t "~a ~a~%" (length (ql:who-depends-on name)) name)))
$ sort -h deps.txt | tail
200 uiop
201 iterate
206 split-sequence
274 closer-mop
344 cl-glfw-opengl-core
350 bordeaux-threads
387 fiveam
391 cffi
408 cl-ppcre
1006 alexandria