Well, the conjecture is at least true. If one lets an engine run long
enough without changing the oil, there will at some point develop enough
sludge to clog the passages, preventing oil from reaching the bearings,
and causing some sort of catastrophic failure.
What we don't know is how long that is, what specific factors influence
the formation of sludge, and how much they influence the sludge buildup.
As for the case in question, if it's actually from an 8700 mile engine,
there was some problem. Either the oil didn't provide the proper
protection, or some external factor caused it to lose it's protection
against sludging. We're not in 1950 anymore.