When Fahrenheit came up with his temperature scale back in 1724, he clearly didn' think about embedded applications. If he would, he'd wait till Celsius invents his scale in 1742.
The problem here, if you use Fahrenheit to tell the temperature and you want to make a thermometer with a microcontroller, you will find out what is voltage on a sensor, calculate Celsius from it, and then convert to Fahrenheit by *9/5+32, right? (right, right, unless you've got a Fahrenheit sensor - which you most probably don't)
So you end up spending more cycles and getting a huge error as a result. That's crazy, guys!