I could be wrong on this, but I think Kelvin is basically required for thermodynamic measurements. Entropy measurements, for example, depend on ratios between temperatures relative to absolute zero. You could still manage using centigrade of course, but you would have to offset all of your temperature measurements by 273.15
Probably a lot of other physical applications that also depend on having an absolute zero reference, but that’s the only one I can think of for now.
Welcome to the crowd! Eventually, you realize that an operating system is just an operating system: something you use to get work done, and the less you notice it, the better it’s doing its job. The pride of setting it all up mostly ends very shortly after you’re done. At that point, you realize that pretty much all distros are the same, give or take.
That said, there are always moments that make you realize that your OS is amazing. When you’re faced with a new and difficult task that you don’t know how to achieve, then you look at your distro’s documentation and solve it in a few elegant steps. And I’m not an Arch user, but that’s when the Arch wiki will really be your friend, as well as all the other resources that Arch has for its users. I can’t think of examples of these kinds of moments because they’re so rare, but those are the moments that feel great and really make you appreciate your OS.