If they go down the route of "everyone is guilty, let's find out what for when they cause problems for the elite", it's often (but not always) followed by rebellion and uprising — I think not usually the people themselves (though that can happen) but rather because the elite don't necessarily agree with each other and build factions of supporters. Even the Stasi fell, despite all their efforts.
When failure can be graceful instead of painful, I think that's better. I hope I'm right and that's not just wishful thinking.
If they get as far as actually publishing whatever it was, that means they never got paid.
The UK also allows private prosecution, but that's going to be more of "personal vendettas between non-elites also get prosecuted" rather than "blackmail" given the latter is also a crime.
If you catch every road traffic offence, the only people who will still have a licence will be people like me who don't have a car.
If the UK tried to fully enforce its drug laws, it would bankrupt itself with all the extra prisons it would have to build.
Even if the governments of the world don't care to use surveillance tech to catch all criminality, blackmailers will use it because it's already cheap and getting cheaper, which forces the governments to change anyway. (Though perhaps GenAI will get good enough fast enough that any image will be assumed fake by default).
But I really do mean radical decriminalisation (civil law offences are not criminal offences) not merely the illustrations of decriminalising hard drugs and reducing the penalties for speeding.