I'm not too familiar with the former, but am I correct in assuming it's less useful, compared to FB proper, for both ads and information gathering?

And with WhatsApp, if everything is indeed end-to-end encrypted, would this not be even more the case? Instead of a steady supply of chats, photos, location data, FB would 'only' have metadata to work with. And ads are probably not really a realistic option at all.

Unless I'm wrong about all that, I imagine the value of these two platforms is significantly lower than the original value of Facebook (to them, anyways)