Americans describe it in this way because in large swaths of America, 100F is more or less the hottest it will ever get, and 0F is about as cold as it will ever

Americans describe it in this way because in large swaths of America, 100F is more or less the hottest it will ever get, and 0F is about as cold as it will ever get. It's not a matter of "getting a sense of the scale". That sense of the scale comes from lived experience of weather, not brief textual descriptions of the scale.