Degrees are used for many things besides temperature. Angles obviously, but is also common in some countries for alcohol concentration (same as %ABV) and other specialized units. Essentially, "degree" means "unit", and "degree Celsius" means "the unit of Mr.Celsius". SI dropped it for Kelvin probably for consistency and because it is redundant information, we already know that Kelvin is a unit, no need to specify "degree". It also adds a funny character to the abbreviation, and would be the only unit in two words.
It isn't because it is a relative scale, Rankine uses degrees and it is an absolute temperature scale just like Kelvin. The difference, I'd say, is that the Rankine scale didn't go though the SI standardization process.
There is nothing special with division, "degree Celsius" is the unit, you can't separate the "degree" from the "Celsius". You can measure a thermostat dial in degrees Celsius per degree (of angle). The resulting unit is just that, not "Celsius".
It isn't because it is a relative scale, Rankine uses degrees and it is an absolute temperature scale just like Kelvin. The difference, I'd say, is that the Rankine scale didn't go though the SI standardization process.
There is nothing special with division, "degree Celsius" is the unit, you can't separate the "degree" from the "Celsius". You can measure a thermostat dial in degrees Celsius per degree (of angle). The resulting unit is just that, not "Celsius".