I totally buy this as someone located in the US, but what is everybody else using? It can’t be WhatsApp? Is everyone sending all their connection graphdata to Meta?
Some places have regional messengers that are very entrenched, like Line in Japan or KakaoTalk in Korea.
WhatsApp is a default option in a large number of countries including most of Middle East, parts of Europe, Brazil, most of Africa, Southern Asia. To me it is surprising, too, because out of all messaging options WhatsApp seems like the least developed and least ergonomic.
And yes, this does mean that most people share whatever data Big Tech wants. They use Meta to talk to each other, auto-upload their photos to Google, click "accept" to every cookie banner so that thousands of no-name companies around the world know where they are and what they are doing at all times.
The only time I ever open iMessage is when I get an SMS 2FA verification code or something similar.
Also, in the Middle East everyone also just uses WhatsApp or Telegram.
Got WhatsApp, because there is no other channel to communicate with customers. It’s literally used by everyone without exceptions. Really scary.