I don't see how this follows. The moment you create/share data with a site, what's to prevent them from reselling it?
The only thing this seems to attempt to solve is portability/interop (and moving control of and responsibility for blocking/moderation/spam to users rather than sites).
I don't see how it helps at all with privacy or you "controlling" who gets your data. If you give it to site A but not data collector B, what's preventing A from selling it to B? As far as I can tell, the situation will remain identical to how it is today.
Your data will never be in one place unless you never share it. The moment you use it with other sites or services, it is stored there too, out of your control.