As I said
It’s just usually using the one with zero offset makes the math easier
You can use Celsius in the ideal gas law. You just have to make sure to include the offset in your calculation. There is no loss of precision by using Celsius, and it isn’t wrong. It’s just the math is easier if you use kelvin, because as you point out (in this case) it’s the ratio of the absolute T that’s important, and a delta T is not enough.
By including the offset in the calculation, you have converted to kelvin.
Yes, as I said repeatedly, the math is easier which is the reason. If you didn’t include the offset in the calculations, you wouldn’t lose precision, you’d just be wrong.
I’m at a loss as to what you don’t understand.
I suspect you may have mistaken me for the first poster in this comment chain. I never disagreed with your statement that precision is not a factor, I was clarifying only that they are not totally interchangeable. Interchangeable in relative measure yes, easy to convert in absolute measure yes, equally precise yes, but they are different things, albeit extremely similar.
