Take a look at the Messages app on your iPhone. Most likely, 99% of the "green messages", that is, those same SMS messages, are not correspondence with friends. SMS messages with two-factor authorization codes from social networks and Internet services, notifications from banks, government agencies, delivery services and other commercial organizations have replaced communication.
In the modern world, such messages are called the general term business messaging, and it accurately reflects the modern essence of SMS messages. We no longer text our friends and do not save symbols, for these purposes there is WhatsApp, Telegram, Facebook Messenger this method of information delivery has turned into a communication channel between the client and the service provider.
The business does not know which messenger the client uses, but it is sure that if he has a phone number, then he can definitely receive text messages. SMS technology in the era of messengers and the mobile Internet still wins in terms of reliability and versatility.