The problem is the ease at which the various identities can be identified as belong to the same person. Very few people have the kind of processes that really

The problem is the ease at which the various identities can be identified as belong to the same person. Very few people have the kind of processes that really protect that online personas from being uncovered. It's non-trivial to ensure that you always associate cookies , IP addresses, browser signatures, behaviour... with one persona and yet never ever leak that to another. Bear in mind that computers are so precise in their work here that you only need screw up once to burn that persona forever. Pseudonymity is achievable, but unless you say nothing and participate in nothing anonymity is incredibly hard to achieve for a single persona. Anonymity is exponentially harder to achieve when you have multiple personas. And this is before you get into face recognition of photos, language analysis, gait analysis etc all attempting to to the real you from the very things that are harder to fake.