WhatsApp is also addressed in that video.
It’s great in countries where it is so dominant that it is everyone’s default. (That’s not everywhere except America, BTW)
Anywhere it’s not 80%+ dominant already, you are stuck trying to convince everyone and their grandma to switch their message app and that just doesn’t work.
Plus… more Facebook on my phone? No thanks. I’m not saying any other company is an angel but Facebook is known to be the devil.