[namelost]

What made Whatsapp popular is that it worked just like SMS. Users are identified by phone numbers, so you can use your existing contact list.

However unlike SMS it didn't cost eye-watering amounts of money to use. Whatsapp never became popular in the USA because most people on pay-monthly contracts received large SMS allowances.

In the rest of the world, networks felt threatened by SMS -- if texts were too cheap then people would stop making phone calls! So it was universally crippled with ridiculous limits and fees. Even in 2018 it costs me a lot of money to send an SMS, and I don't know anybody under the age of 35 who uses it.