The freezing point of water is also a great place to zero the scale

I disagree. Realistically the scale shouldn't be able to be negative at all. It doesn't really make any sense for something have a negative temperature.

Imagine if other scales worked that way. An object can't be negative centimeters long. Light can't be negative lumens. You can't score negative % on a test. If you are measuring something you can't have less than nothing.