[mttddd]

Ignoring for a second the NSA sitting in the middle sucking up everything I think a lot of this is just down to domestic law enforcement wanting the status quo.

Currently you send an email/message and its encrypted between you and Google/FB/etc, they have a decrypted copy, and the encrypted copy is sent on to the recipient. Governments can submit a subpoena (or whatever the local equivalent is) and get copies of that communication. They can also require said companies to monitor those communications for child porn. With E2EE encryption all that goes away and combined with things like iPhone encryption you end up with a situation like Pensacola where the FBI cannot access the attackers messages without brute forcing (or however they cracked) the device itself.

I also suspect when they say Big Tech they really mean Facebook. One Facebook is the company most prominently moving in that direction. Two unlike most existing encrypted communication apps where you need to know the persons phone number or username, FB/IG allow you to search for and identify potential victims (e.g., child predators) or others sympathetic to your cause (e.g., ISIS) and subsequently contact them.