The difficulty is that unless you make these kind of platforms illegal, people who engage with them in ways that enhance their reputations will have an advantage over those who choose not engage with them. And most people will always choose to use them, not only because they're convenient, but because people love an opportunity to enhance their own image in public.
For these reasons, I think it won't be possible to convince most people to exercise their right to privacy. What we should do instead is try to make society as tolerant as possible, so that there is no penalty for how you present yourself online. Urging people to exercise more privacy in fact has the opposite effect, because we hear fewer diverse viewpoints, and those who exercise their privacy come under greater suspicion.