I don't think that's the case.
Bill Burke has a DVD in which he uses a Hi-lift jack, Hi-lift jack winch adapter and tensioner, a 3/8" chain, 3/4" D-rings, a tree strap, a 2" recovery strap and a Amsteel blue winch line extension in order to hand-winch a vehicle over flat terrain with a Hi-lift jack. The Hi-lift was the weakest link at only 5k lbs, which is consistent with your theory.
However, there's also a segment in the video in which Burke uses a 3/8" chain along w/D-rings and a tree strap as an anchor around a boulder for a snatch block so that he can double-line pull his Land Rover up over an obstacle at least 6 feet high. The chain was the weakest link in this case at 6.6k lbs and the tree strap was probably the strongest. The winch (the "tool" doing the work) was probably rated at 9k lbs, in between the two other pieces of recovery gear.
The latter demonstration contradicts the theory that you should only use recovery gear that has a higher WLL than the "tool" doing the work and makes the case (which is the mostly logically intuitive) that you simply need to avoid exceeding the WLL of the weakest piece of equipment being used.