You heard the same spiel as me from the same individual. So not putting words in anyone's mouth since I think it's safe to assume we both respect the source, the question comes down to multipliers for slope and mire factor.
All points are rated by the OEM based on GVM. Which as we found out is the case for all connection points they put on the vehicle (e.g. screw-in tow points, tie-downs, recovery or tow hitches).
The difference is the SAE and various standards have different ways to rate them. I didn't write it down, do you remember Paul if it was 50% or 100% of GVWR for these? My memory is 50% to avoid distorting the vehicle chassis, which is why it's questionable.
In any case the key being in a situation like this the three variables are:
- vehicle weigh
- slope
- surface
Weight is weight.
Slope is 25% of weight per 15° of slope.
Surface is 10% for pavement, 25% for grass or hard packed material, 50% for gravel, shallow snow or mud (only stuck at tread depth) and 200% for mud, sand, dense snow at hub depth. Highest regular case is body deep mire, which is 250% of weight.
Say the vehicle is packed to GVWR of 4,000 lbs, on a 15% slope and that's not quite mired to it's axles on hard packed snow, so likely to fall between 0.50 and 2. Say a straight 100% multipler for that. Totally willing to admit that if it's sitting on top of hard packed snow/ice it could also be in the 10% to 25% range, too. That's important to think about during assessment.
4000 x 0.25 + 4000 x 1.0 = 5,000 lbs estimated force. The pull you did may have been at 125% or 250% of its rating, so on the wrong side of capacity with negative safety margin.
BTW, since hard surface pulls are 10% of weight you can see how those don't need full GVWR. A 4,000 lbs GVWR vehicle getting pulled from pavement onto a 15% tilt aluminum flat bed needs to stand up to just 4000 * 0.10 + 4000 * 0.25 = 1400 lbs force.
Obviously the OEM builds in some margin, it's not a definite fuse per se.