I am not a fan of Facebook, in fact quite the contrary. But you do have to give them one credit, they understand Social very well. HN audience is not something FB targets. The world outside HN is quite different and loves FB, Instagram etc.
I'd bet that there's more of that happening on WhatsApp than any other app in the world, possibly by an order of magnitude.
You can't separate the company WhatsApp from the company Facebook because they are the same company FB.
There has to be some sort of magic there. Maybe someone with more experience in the space can offer more insight here. But it just astounds me that Facebook has managed to generate at least an order of magnitude higher ARPU than Twitter, Snap, Reddit, etc. They're making as much per user as Netflix does from actual paying subscribers.
I find it hard to get excited about this.. probably will get cancelled in 6-9 months after languishing a bit.