it was in part for people who didn't understand, and would call for service(which they had to pay for if there was nothing wrong with the machine) alerting them that this selection gave them a cold deep rinse, and the spin/spray was warm...
for many setups, the hot water in the pipes has cooled down by the time it called for the spray rinse...so you got a full flow of cold water from both sides, by the time the hot water got to the machine, the spray ended....unless your machine was located very close to the water heater, or found a way to purge the line before the final spin started....