No, the tyrants of the past didn't need evidence once they'd decided who to go for. But if they'd had this kind of information it would have been so much easier for them to identify anyone who might be any kind of problem to them.

Not just the DNA stuff on its own - put it together with the surveillance cameras and the data from identity cars and credit cards and computer search engines...

Every bit of the information network makes sense on its own, including the DNA bank - but put them together and the possibilities are frightening. There have to be ways of protecting us from that kind of power, and holding the people in authority strictly to account. And we certainly don't have those effectively in place yet.