Originally Posted by 3alarmer

...ball bearings and how they work have been thoroughly researched. Cone and race surfaces are case hardened, at the very least, in a quality bearing assembly. I honestly do not see how what you have described can occur.

Certainly excessive bearing load (to the point where the wheel no longer spins freely under the weight of the valve stem) ought to be avoided. But like @davidad, Mr Brandt, and a lot of other people I have preloaded both headset and wheel bearings on bicycles for many years now, with no noticeable ill effects.

But I'm a test subject group of one, which is why I asked for a source.