To my mind the killer is event organisation. Put it this way: Meetup is apparently a viable business while charging money for a less-good version of something Facebook offers for free-at-point-of-use. No-one else really competes in that space at all (group chats aren't suitable because people who can't make a given event end up being spammed with all the details of it anyway, while people who join late miss out on details that were posted earlier).

Where I live, everyone uses either email, whatsapp or public spaces to advertise and organize meetups, from my sister I know that most parties are orgnaized over WA or Instagram, nobody likes using FB for it.

There is really no point in switching to Facebook from Instagram and WhatsApp since Facebook is going to do it for you.

Everyone is on WA and i prefer it too, but I still need their mobile number, so it's more for close friends/family. I communicate with some coworkers i hang out with on Messenger because i haven't bothered to ask them for their number yet. However, i have definitely reduced my FB usage to an absolute minimum, which is mostly a couple of bigger groups I am part of. Instagram is kind of limited as a messenger. At the end of the day, be it FB, WA, IG ...it is still FB your giving your data to ;)

Instagram and whatsapp ARE facebook..

They are facebook the corporation, not facebook the website.