I stopped using Facebook and just started phoning and texting people a few years ago. Almost all the contact you have with people on Facebook is fake, it’s mostly sharing memes and news. It’s more personal to do that over the phone. I think I’m closer with almost everyone since leaving Facebook. Most of my contacts have installed signal of their own accord at some point too which is weird but pleasant
This probably works ok if all of your friends live in the same country as you (and that country still widely uses SMS). However it turns out that international calls/texts are still an expensive minefield, and folks who move around internationally don't have stable phone numbers (since those are tied to country). And as a result, WhatsApp/Messenger is the only viable communication method for a lot of folks.
If all your friends use WhatsApp/Messenger sure that works. However if you have friends in China you need WeChat, in some places Line is the main platform. Some people tend to use Google Hangouts or FaceTime only . A lot of friends do not want use any FB products and will use Signal/Telegram etc
Even if SMS is expensive, email is still quite free. It works almost like SMS/messaging on phone, you get push notifications on your phone and you respond.
I move around about countries every few months, keeping a VOIP/Skype phone number as the number anyone can reach you at works for me, while my local number is more for getting an internet connection and occasionally for signups to local apps (like rideshares, food delivery etc) that reject some VoIP numbers .
