If you think oil and lubricants need to be warmed to a certain point to not harm the engine, why would it be any different if you were idling cold or putting it under light load cold? It wouldn't really. Old cars needed to be warm for the carburetor to provide the correct air and fuel mixture. It didn't have anything to do with lubricants. Once cars became fuel injected it became a waste of gas to warm up the car idling. The engine actually warms up faster being driven.