The paragraph in https://koha-community.org/manual/18.11/en/html/systempreferences.html#staticholdsqueueweight-holdsqueueskipclosed-randomizeholdsqueueweight saying Leaving StaticHoldsQueueWeight empty is contraindicated at this time. Doing so will cause the build_holds_queue script to ignore RandomizeHoldsQueueWeight, causing the script to request hold fulfillment not randomly, but by alphabetical order. is talking about (without mentioning it by number) bug 8562, which was fixed in bug 12803 comment 14.
Fixed in https://gitlab.com/koha-community/koha-manual/commit/906bede20e19fc22578a18d2ca043b4747fb14ba
Found another mention of this in the 'holds queue' description. Will make a merge request to remove.