Whatsapp was never about apps and never about anything but messaging. Integrating any of the features that make money for FB would've driven users away. The only thing they brought to Whatsapp is Stories (apparently all apps need this now) but I don't know anyone who uses it on Whatsapp. It's always empty on whatsapp while people happily use it on Instagram.

I can't imagine how the Whatsapp acquisition will ever pay off. It doesn't need to because they make money with FB and Instagram but I don't see why they had to buy it..

Others have touched on this... but I bet it's also to lock down that market space. Facebook's competition is communications platforms. By preventing anyone else from dominating the secure communications space, they don't face that threat.

I think they bought it purely to prevent it evolving into a competitor. It's got too many users to kill off as a product, and at least they are 'Facebook' users in a roundabout way, and by not adding anything anything new to WhatsApp they can keep it subjugated. Keep your enemies closer and all that.