Steve-
I have used Wendler's formula for estimating 1 rep maxes for my students to keep them progressing without hitting a true 1 rep max. I only have a year of experience using this with others (I've used many in the past on myself personally) however I feel confident that using more than a 2-3 rep max in a calculation leads to unrealistic true 1 rep maxes.
You are correct that one CAN possibly generate x times (bell weight) of force using hardstyle swing techniques, and yes both the swing and deadlift are loaded hinges, however the beginning position to each is far different in that the bell is either out front or loaded behind the hips opposed to the barbell in front of the shins. Many are held back in their deadlifting by movement issues, lacking enough mobility to assume an optimal starting stance, and/or motor control to fully build tension from a MUCH deeper starting hinge position than the swing. In a swing we can hide these issues, a one-rep max or near max deadlift we cannot.
Personally my deadlift has been stuck around 400-415 for many years, a little over 2x body weight @ 6' 2". My swing, including one arm swing and double swings have continually improved over that same time period, having no effect on my deadlift, so obvious the quality that holds me back from a higher deadlift is not associated with a WTH benefit I can receive from swings.
I think most people's hang up in these comparative mental experiments is that we read Jane did x times loaded pull-ups after S & S, and Bob's press improved x # of kg's while Timmy finally deadlifted 3x body weight, and don't forget that Mary finally did a pistol on both legs. We then perceive we will receive similar benefits in ALL these areas from one program, then get impatient and program-hop the one time we test a press, pull-up, etc. and don't see this unrealistic carryover that was a product solely of our imagination in the first place.
Re-read Tamer's advice several times and pick goals that are meaningful to YOU, that make you gain health AND strength, goals that serve your highest purpose and the challenges you are learning from in other areas of your life. Many (maybe most?) specimens we compare ourselves to have yet to do A swing, let alone the S & S with a 32kg. Al's discussion of genetic gifts is important, those who are amazing athletes are a product of fortune and environment.