It was sarcasm. I’m very aware how a cooling system works.
When an engine is cold it needs a much richer (more fuel) mixture to burn resulting in a dirtier and inefficient burn. So a modern car tries to get the engine up to operating temp as quickly as possible. So when the engine is cold and you start it, the thermostat acts as a valve to prevent coolant from circulating through the radiator, to quickly warm up the engine. Then when the coolant reaches the thermostat temp it opens to allow the coolant to be circulating through the radiator. Once this occurs (open loop), the thermostat stays open and has no other effect on operating temp.