[Santosh83]

Not friends. Networking. Let me give you a concrete example. My wife is an animal rescuer and she coordinates her activities with the rest of about a few dozen rescuers in this city, and thousands across the country, almost completely on Facebook, or ocassionally on Whatsapp. It is realtime, convenient, real name based and privacy settings exist to block trolls and nuisances.

Now what do you suggest she use for her communications? Plain old telephone? Or email lists? Neither are anywhere near the convenience of Facebook. And these are all non-tech folk, so suggesting they host their own BBS or some such option is a total nonstarter.

The point is, millions of people across the world use Facebook for similar use cases. Yes, they could ALL take the time and effort to learn some tech and migrate to another platform. But that's like asking the majority of Earth's people to become self-sustaining permaculturists. It's very unlikely to happen.