>> Yes. You are describing actual police work; it is how things have always been.
> No, it hasn’t. Criminals haven’t always had access to literally uncrackable encryption,
As a preamble, police already have a vast array of new avenues of surveilling citizens. They have this now and it gives them massively more access to our private data/comms, than ever before. There is little that LEO/Govs/Corps don't have access to already.
Police have never had at-will access to any personal data and communications they desired.
Until very recently: To find info they wanted, police performed police work and commonly found some degree of what they were looking for. But often it was nothing. Under this, society thrived.
What police have right now is massively more than that. In the few spaces where some content might be denied them, they still have the associated metadata which is valuable on it's own (often more so than the contents).
Historically, you and I have always had options and methods of keeping our personal info and our private comms out of the reach of police, govs and other powerful actors. It was good for us and promoted a healthy society.
We have lost most of that. However, using robust encryption we can keep a minuscule portion of our total comms and data out of their trivial reach. What little it is - it is still good for us.
Historical privacy was what we had. Under that condition, societies were healthy and thriving.
Persistent, pervasive surveillance is what we're moving (rapidly) toward. It promotes other types of societies.