I'd say at this point all major tech companies, ISPs and authorities should have more enough information and disabling and freezing their accounts would be the first step.
This can happen if you delete your old gmail account. Source: I deleted a gmail account I shouldn't have years ago. It will say taken if it previously existed, and was deleted.
The google account: "Couldn't find your Google Account"
The email: "50 5.1.1 The email account that you tried to reach does not exist"
But then when you try to register it says it's taken.
Was it disabled?