The problem is LEOs (and associated industry) claiming that enforcement is impossible without the ability to obtain cleartext.
This is a lie: obtaining cleartext just makes enforcement vastly easier and more scalable. If crims have encrypted mobile phones, you can still point a microphone at them.
Honestly, I had always assumed LEO wanted access to decrypted message content so they could sell it to advertisers. I mean sure, you could catch a criminal or two, but with all that non-criminal data, just imagine how much off-the-books revenue you could accrue by selling it to the AdWords guys.
This is a lie: obtaining cleartext just makes enforcement vastly easier and more scalable. If crims have encrypted mobile phones, you can still point a microphone at them.
Scalability is the big issue.