I might catch flak for this, but I understand Fahrenheit made a ton of sense of an illiterate bygone era (well, I guess coming back maybe)

The vast majority of people were uneducated. Decimals were a non-starter, maybe negatives were also difficult?

0-100 was very easy. Under 0? Don't go outside if possible. Over 100? Don't go outside if possible. >50/halfway? Time for a coat. Having the same scale from -15 to 40 might have been confusing and not centered for them?