High Range, Australia 
How would this help? If I understand it right, you are supposed to upload photos that you've taken yourself. What about pictures taken - maybe secretly - by someone else? They won't have the same digital footprint...right?
The footprint isn't relevant. They're going to set a learning algorithm to recognise your body bits in the same way they can (already) pick your face out of a random stranger's photograph.

I'm just not convinced that we're being told the correct underlying reason for making this request and it can lead to some pretty awesome power. Imagine a politician snapped in bed with somebody but the face was obliterated or obscured. Facebook can tell you who it was. From a marketing viewpoint, they can present ads for swimming costumes using somebody who's a close match to your body style and avoid the "I'll never fit in and look good in something like that" response. They can also determine with a high degree of accuracy what colour or shade of hair you were born with (the areolas hold important clues). I see it as just a power grab for information they don't already have and probably shouldn't have. What do your private bits look like? If it is extended to men (and it probably will be), they can now trace all the anonymous dickpics and tick the 'circumcised' or "ooh, that's long" bits on their hidden advertising profile.

What's really scary is the number of people that will volunteer this information without question. We know the narcissists will. But so will hundreds of millions of other people just because "everybody else is doing it" ...
Brrr.... That's one of those "I don't want to hear it because I don't want it to be true" moments.