Because time is a social construct and humans have no business having any form of social norms or social rules. It's not like humans are social creatures. Abolish all the social constructs!
I know, it's the weirdest thing calling folks. People pretending like calling others with a phone is the purpose of them. Jeez, the audacity. Not following social rules of using a phone. People need to construct some socially agreed concepts to help cooperate with each other.