I can only speak for TWA although it may have been (or is) an FAA requirement. Without FD and or autoflight it was LOC MDA for DA and, if I recall correct RVR of not less than4000
Or it could be airplane specific. Checked our current 744 MEL, no A/P has no effect on mins except no CAT II or III. No F/D limits us to LOC minimums. Can't remember any hit in the 727. Used to fly planes that didn't have an A/P or F/D under 121 to 200/RVR1800.
There used to be a funky CAT I ILS to 21L at KDTW that required a coupled approach. As I recall, something about the tail of planes parked at the old international terminal being inches into the protected airspace.