It is end to end encrypted but facebook controls both ends so... ?

That's not how it works. They won't be able to see the messages themselves if it's e2e encrypted. You can say they are lying of course

Yes... meta data

Is metadata useful for ad targeting?

If the claim is that they use the content of messages that's be one thing, but what kind of ad value is really pulled out of timestamps and phone numbers of who you messaged?

That said, collection of metadata can still be a problem, I just don't see the ad value.

Yes it is useful. Knowing who you contacted and when tells advertisers demographic information and probably more that I can't think of

What demographics can be gleamed from who and I contact and when?

This is one of those times where I feel like I'm annoyingly peppering someone with questions, hopefully it doesn't come across that away. I really am curious what ad-related use case I may have missed with regards to metadata.

OMG, that's such an obvious word play that has such dire ramifications. FARK!!! I have to hand it to theZuck, this totally changes how I look at the name change