I ran into this same issue earlier today using the Wraith cooler included with my Ryzen 5 2600 on an MSI B450 backing plate, but I was able to confirm that the cooler managed to strip all the threads out of two of the four holes on the backplate.
It happened after I had gotten one screw started and moved diagonally across to the other. Once the second was started and I was tightening it, the first screw yanked itself out of the back plate and took at least the first thread with it. When I tried to re-seat this first screw a second time it simply would not engage the threads without stripping them out. After four attempts (including new thermal compound with each) I was unable to get the Cooler on at all.
Looking at the screws on the cooler itself, there only seems to be 2-3 threads on the screws themselves. Combine this with having to apply significant pressure just to get the first thread engaged and it results in a lot of load on a single thread. This design makes it incredibly easy to strip the backplate or screws unless you somehow manage to get them all started perfectly even across the whole cooler. This could be solved by just lengthening the screws so they'd engage the backplate without pre-loading the springs.
From what the orignal post says it sounds like they've run into the same issue I had. I managed to find an aftermarket cooler that wasn't expensive, it seems like you may have to do the same.
