Earlier quoted context omitted.
How many people can you reach with WhatsApp, Telegram, Signal, Messenger? How many people can you reach with SMS? Relevant XKCD: https://xkcd.com/2365
A lot more than with SMS. You can send someone an SMS but they are not going to respond because either they cost money or they have some tiny allowance of them.
Also I have a dumbphone and I am the only person my friend send SMS too. That makes me quite a unique person !