It makes sense for `Enum.find` to return `nil` because the reducing algorithm have a "not found/nothing" result, because it makes sense to find "nothing" in a list.

The maximum value of nothing doesn't make sense though and the maximum of nothing is certainly not `nil`, so it should raise.

And for `reduce/2` it is even more important to raise because we don't know the reducing algorithm. So we don't know if `nil` is an acceptable result that would make sense.