I swapped my keys around for Dvorak. I moved almost every key, and they all still work. But, I can see their hesitation. It’s really easy to mess up.

I think what he meant it is doesn't always fix the problem for problematic keys.

For me, it has always fixed problems of keys that stopped working, but it doesn't seem to necessarily fix keys that double press. I assume that is related to an issue of the membrane itself or something under it.