Re: "using people's cellphone numbers, provided for 2FA to target them with adverts"
Another article explaining the same "Shadow Profile" thing:
In case anyone isn't aware (I wasn't), where you might expect FB to allow advertisers to target people by obvious data like location, age, gender and things like "interests", they also allow advertisers to target users by their email address or phone numbers. Which means that advertising can be super-targeted... a clothes shop can target their own customers via FB with advertising in the full knowledge of what they've previously purchased.
And like that isn't bad enough, the information that is used for targeting includes phone numbers that are supposedly only used for two-factor authentication.
Aaand if that isn't bad enough, it can include contact details that they've skimmed from your FB-friends who have allowed FB access to their contacts.
All this stuff is part of a "shadow profile" and they won't tell you about that or let you download it.
This might be obvious to others, but personally, whilst I'd guessed they would build a profile that would place users in broadish categories for interests and perhaps infer a bit more data from that, I didn't know advertisers could target people so specifically. Which is really terrifying when you consider political campaigns.