It really isn’t.
That’s nice for them. In Python, we have min and max functions that are under no obligation to work like minNum and maxNum. In practical terms, either you care about NaNs or you don’t. If you don’t, filtering them out is trivial. If you do, an exception makes as much sense as anything else.
It’s not maths. It’s Computational Mathematics, which is a whole different ballgame. We didn’t even touch it in the Maths part of my degree, and we held it at arms length and whimpered in the CompSci part.