The powers that be, or at least their voices, like to cite the potential abuse of cryptographic tools, in particular how they can be used for crimes without any means for a paper trail to be discovered.
The truth is, however, the greater abuses occur systemically, put into motion by those self-same powers who are upset that they no longer have a monopoly on privacy, and the lapdogs willing to sell any information at all to the highest bidder. And those abuses are happening, they're not some hypothetical or theoretical state of being. Therefore, a solution is required.
This is also why #Signal are making plans to be on their way out of the UK. Recent legislation passing through Parliament brings with it the goal of making all communication accessible to the government -- no matter the human rights issues involved (which the Tories, as always, are salivating over).