Telegram can be used on multiple devices simultaneously. Syncing the private key for each chat across multiple devices can be an issue. That's why secret chats are only available on the device they were created on, and having encryption on by default would not make sense.
Just fine is a bit of an overstatement for matrix. I think it got much better now, but the user experience for multi device key syncing on element and other clients gives room for improvement. I ended up having to reinstall because I could not figure out the mess I created myself. There wer so many keys involved that even having a PhD in computer science I could not easily grasp their meaning and function. I understand at least why key syncing ist not easy and I understand why someone would not support it. I however do not understand telegrams choice of obscure crypto as well as it does not make it easier to support this. But I guess their business model (pushing contextual advertisement into chats) relies on not having crypto.
I agree, but most of these issues stem from not having enough funding, as active as matrix seems to be, they are struggling to actually fund its development.
Whatsapp being e2e is almost (but not entirely) worthless, it tells me that they are likely not training LLMs on my messages, but I have zero trust of their safety from client-side backdoors.
The security of e2e cannot be higher than the security of the clients
AFAIK, whatsapp is still dependent on your mobile being the primary source. It has "link a device" feature, which has some of the features but cannot be used as an independent client. For example if you're using the web version and want to see some old chats, you can't unless you use it from your mobile. WhatsApp's encryption keys are tied to the device, not the account. In Matrix, encryption keys are tied to the user's account, not the device, and thus it wont be an issue.
> AFAIK, whatsapp is still dependent on your mobile being the primary source. It has "link a device" feature, which has some of the features but cannot be used as an independent client.
"Not all messages and chats are synced to linked devices from your phone. WhatsApp Desktop syncs more message history than WhatsApp Web. To see or search your full history, check your phone."
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.
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.
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.
