WhatsApp acts the phone's entry point for many.

Contacts aren't stored on the phone, messages act as contacts. Phone and video calls also on WhatsApp. Photos are shared via WhatsApp so that's where the gallery is. It even functions as a calendar of sorts – events are organised in WhatsApp groups so there you have directions and dates and who brings what. More and more businesses use WhatsApp to communicate with customers.

Why people like this, I do not know. But this is what I observe. Maybe software in general is too shit to use so people prefer to take a sub-optimal WhatsApp-based life over fighting their phones at every step. And I can't blame them.