So here's my take on it. If you look at the factory emergency jack, the pinch weld is used ONLY to locate it inboard/outboard on the car. The jack itself doesn't even touch the pinchweld vertically. All the weight is supported by the pad just inside the pinch weld.
The pinch weld is used only because it's easier than trying to correctly position a jack/jack stand behind it.
I think that's the REAL jacking point, not the pinch weld. in fact, I believe this enough that i made this:
I don't recommend turning the jackstand sideways though....that's just asking for trouble when it slips off.