I think the main difference between Twitter and Facebook is that the former is very clear at all times that all your data is public (by default), while the late

I think the main difference between Twitter and Facebook is that the former is very clear at all times that all your data is public (by default), while the later is moving from a private to public data, in a not so clear way. But being more focused, Twitter does have an edge: it does not try to contain all data about your life, therefore, even if it sells your data, it doesn't really matter, as it was public already (buyers could just as easily use the API) and you don't have a lot of info about you anyway (unless you choose to do so). Summing it up: would we even be having this conversation if Facebook, from day 1, started with defaulting all data as public, being clear about it, and making data securing hard to accomplish?