You’re right, the Celsius scale doesn’t span across one particular ‘topic’- but either end point is not only relatable, but specific. You’ve got snows/frosts/freezes at one end, and boiling at the other. Both of those will always happen at that temperature (more or less), but different people will feel comfortable or not in a hugely wide range.

But then my crusade for metric time would seem silly

A denominator of 1 makes it even simpler