[adboofer]

because telegram has group chats and channels, which are also accessible cross platform, it doesn't make sense to turn on e2e by default. secret chat feature is encrypted and thus only available on the device you start it from.

[jacooper]

What does being multi platform have to do with E2E? Matrix does the same thing yet supports E2E, whatsapp allows multi platform access while also having full E2E support.

[adboofer]

In whatsapp, there is a primary source (your phone) and you can "link" other devices with the primary source. This is different from how telegram handles it. In telegram you can use sms login to use the client from multiple clients, within the same smartphone, or different devices. With whatsapp, you can only have one sms login device, which would be primary device. If you use sms login with another device, you wont be able to use the previous device. To overcome this, it has a feature which can allow you to link your primary client with other clients but it is janky and does not have all the features. For matrix on the other hand, the encryption keys are tied to the account.