I never said it's a good starting point at all. Ideally it would be 0, where C gets it right IMO. But the range of 0-100 is a range most Americans are going to use at some point. Our climates vary vast even by driving just 200 miles or even less. For example, while it may be 60 F here in Phoenix, I can drive to Flagstaff 120 miles away and it could be in the 30s.
I guess I just like the range better considering I've lived in many climates here in the US. If the US switched to C, I wouldn't cry about it.