this may be true for a commercial razor maker, but a custom maker, isn't turning out thousands of razors, they are hand making them one at a time,, the grinders your talking about have been with the big boys a long time,, but even then the razor makers from Solingen were turning a lot of razors out with out, and they were the kings of hollow grinding.

ive ground a razor to full hollow and heat was never an issue,, that's only if your not paying attention Tc