It would be useful because it gives multiple specific and relatable reference points. How is that not useful?
The way humans relate to the temperature has a huge range and so very vague. Do you say that 0 is when you swap shorts for trousers? Or when you put a hoody on? Or is it when your neighbour puts their hoody on? Or when your friend from Texas puts their hoody on?
It’s like when you come across a recipe that calls for a knob of butter. Everyone’s knob is a different size, we’ve just agreed to say that whatever it is, it’s enough.
It doesn’t matter what other people think about the temperature, it only matters what you think. Fahrenheit is useful in the same sense the word Red is useful: you and I could be seeing totally different colors that we call red, but it doesn’t matter because we both point to the same objects as being red.
