This is not true at all. Not only do they still have all the powers they had over phone calls and snail mail, they have a massive advantage over those days with the
Regulation of Investigatory Powers Act 2000/Part III which allows imprisonment for up to five years for not revealing a key that the police BELIEVE you have. They do not need to prove you have it, and after the five years they can always ask again and lock you up for another five years.
This is all about letting them look at the data without either a warrant or your knowledge. And I will repeat, it does nothing to advance the stated aims.
Exactly what problems clearly need a solution, and what laws we could introduce to solve them is the point of this thread. I agree that the problem of unfettered data processing and autonomous weapons are significant and deserve a lot of attention. The current government suggestions about encryption seem to be much more effective at clamping down on a popular movement such as environmentalism than harmful pornography, and no one has even tried to make a cohesive argument to the contrary. They are very likely to damage the UK economy. I see nothing to support about them.