Facebook helps a lot to stay in touch with people you meet while travelling, ex-colleagues, or people you just occasionally meet in general and that you don't have the phone number of.
It's not as good as Chinese wechat though, because it's really spammy: you click on like, everyone can see. On wechat you only see photos, likes, comments, from your direct friends. It is much more private. Once you've tried it, it's kind of hard to put up with the very public nature of Facebook, I find.
People use what they got. Most businesses accept American Express. So people carry it in their wallets. Network effect. Facebook is a good meeting point. Its hard to be pedantic on things that literally will kill minor relationships.
Well, there's an opportunity. Five years ago, everyone in China used to use qq, which is kind of like Chinese Facebook: everything public. Then wechat came out, and now I never use qq any more, I mean, noone does.
Both qq and wechat are owned by tencent.
They are. Not sure that changes my point much? The user database/registration are entirely separate. There is no lockin being circumvented by virtue of both being tencent.