True enough, but how much revenue is FB bringing in on these platforms? These platforms all have alternatives and aren't exactly sticky. If FB turns the screws to increase ROI, customers are going to leave.
I guess FB has the advantage of being nearly ubiquitous in some countries. With the amount of information they collect on their users, I bet they won't have trouble monetizing their platforms in time. Some companies are already using Messenger to interact with their customers. Frank & Oak is an example. There's also WhatsApp for business.