C goes 90% of the way there because 90% of temperature usage in science is for delta-T. That said, you need to be aware of it so you don't accidentally use the occasional absolute temperature in C at some point.

Yes, C is useful in science because it's commonly used, not really because of any inherent usefulness. The network effect is the usefulness, and if F had that network effect it would be just as useful.

A Kelvin temperature is just the Celsius temperature +273°.

I care very much about the freezing point of water outside. It means ice on the roads.

0F is also works for that application too in a slightly different way, it is when a salted road starts to freeze back and becomes slippery again.

My point was about in the chemistry lab, not outside.

I don't work in a chemistry lab. But why is the boiling point of water not important there?

It is important, but more important is having absolute 0, which Celsius doesn't have.

The other problem with Celsius and the boiling point is that the boiling point changes depending on air pressure, which changes depending on elevation. So it's not always 100°C.