15 year olds definitely want to have "compatibility with different systems" including the source of their pay packets, allowance, and access to resources - ie old people and their old email. But it turns out email, even if used infrequently, is still important. It's easy to have multiple accounts sit there indefinitely. Not controlled by one fatcat pulling privacy strings and strategizing your online activity. Meanwh…
To be clear, Facebook doesn't tell any advertisers any information about any users. Advertisers tell Facebook what kinds of people they want to see their advertisement, and Facebook shows the advertisement to those kinds of people.
I wonder if it holds true worldwide and for smaller brands...