At least on older hardware, number of reboots was a stronger correlative with failure than hours on.

I'll readily admit this may have been apocryphal. It was a common adage when I was a child in the 80s and now that I'm actually qualified enough to suss out such a statement I've never cracked open the historical literature at archive.org on this one to actually check.

It could just be a portage from incandescent lightbulbs (where this is true) and older cars (where this is also true). The idea of non-technicals thinking magical computer dust having the same problem is understandable