Ok, understand the downvote. Probably should have caveated it with 'in my social circle'.

In my country, there was no universal messenger app circa 2010s except WhatsApp.

Not everybody had a Facebook account to use Facebook Messenger, adults did but children and elderly didn't. Not everybody had an Apple device to use iMessage.

Nobody knew each other's email outside of work and business - the digital revolution came much later than the US to many parts of the world, and email was a tool for personal communication only very briefly, and only if you already knew that person's email, which most likely you didn't.

The reason WhatsApp took off is because it didn't require anything other than a person's phone number - which was usually the only type of digital pointer you had about a person.

SMS was not an option - it was expensive and limited (to this day still is, unlike the US!), only used as a last resort.

I'm sure many countries around the world would share the same sentiment, though maybe not most. Esp. Europe and South America, probably.