> If they don't have WhatsApp
Is this really likely? I would guess only 70 year olds don't have WhatsApp.
Seems more likely you forget the impoprtant phone numbers because you never enter them manually.
With iMessage, Discord, and Signal, I can't imagine a use case for me or anyone I know to use WhatsApp.
WhatsApp is not universally used. Line, WeChat, and KakaoTalk are more common in East Asia
In the US, the only people I know who use WhatsApp are immigrants who use it to talk to friends and family back home.
lol not 70, no Whatsapp.
Nobody in my friend group has a WhatsApp and I'm a millennial.