[throwaway4aday]

You're missing the point, it's not a case of "we've identified zirgs as someone we want to punish so let's go through their browser history to find a reason to do it" a tyrannical government hardly needs to go to such lengths as you point out. The nightmare scenario is you get people in power who say "we can make the world a better place if we just eliminate all the people who do X" and they have the digital tools to simply filter all citizens by X and get a nice big list they can hand out to the secret police.