Criminal communications have always existed, and I don’t buy that a smartphone is a fundamental change from encoded letters, whispers, or any more primitive signaling device. With an electronic surveillance warrant it is easier than ever to compromise communications. If they suspect that a crime is being committed they should use the existing legal framework that exists for exactly this purpose.
Most (I would hazard > 99%) people won't use this capability for criminal enterprise.
Some would. Some do.
BTW, This does not mean that we should open illegal backdoors to our end-to-end encryption. Private communication must remain possible and viable and easy for everyone.
It also does not mean that law enforcement should resort to unconstitutional means (at least in the US).
But, this is just a different game than what they are used to. It is okay to acknowledge it and resource them to do without.