253
Is Telegram really an encrypted messaging app?
(blog.cryptographyengineering.com)
This is a most excellent place for technology news and articles.
You probably didn't ever meet non-IT person(or most of the IT people). To use e2ee means you need to keep your private key close and safe. 99.999% people can't do that. So when they lost their key their conversation history is gone and it's your fault not theirs.
Signal does this by having your data be unencrypted at rest on your device, and I think that's a reasonable tradeoff because it protects the most import part: data in transit. Or you can be like Matrix and require/strongly encourage setting up multiple clients so you always have a fallback (e.g. desktop and phone). There are reasonable technical solutions to the problem of making an E2EE chat system.