Why does stale grain flake and fresh grain smear? I went and looked, because that's the whole Kellogg story — boiled wheat left sitting too long, run through the rollers anyway, and instead of one sad sheet it broke into separate flakes. Dried starch won't stretch, it fractures. He died in 1951 at ninety-one, rich off a batch nobody would have blamed him for binning.
The patent's really a dimension: two chilled rollers held a fixed gap apart, and the flake is whatever survives that gap. Cooling matters as much as spacing, since a warm roller lets the dough stick and you're back to one sad sheet.
He put a lot of that money into a bird sanctuary near Battle Creek in 1927, back when Canada geese were thin on the ground in that part of Michigan. Still run as a reserve. The geese have never once said thank you.