It is a trade-off between security and usability. By default, you get usability (e.g., you can chat across devices easily). But you think it is worth the cost, you can make encryption keys unavailable without corresponding devices (create secret chat).
My guess, most telegram users prefer usability or don't care/ignorant. It would be a mistake to make the experience worse (that people would notice ignorant or not).
Not end to end. Let's not sell SSL connections as encryption please.
You cannot say "it is not correct" without proof. We know all messages not just E2EE are wrapped in encryption on their way out a Telegram client and we know they are decrypted on their way in because client source code is available.
Why don't you have a look for yourself then let us know if you've confirmed your suppositions?
At this point you are just willfully throwing around misinformation. A number of commenters have tried to point you directly to the docs to which you've just said, "it's wrong".
> talking about MTproto, which is only used for their e2e chats.
This is also misinformation. [1] Please stop.
I only flag as an absolute last resort here on HN but you are actively harming discourse at this point.
[1] https://core.telegram.org/mtproto/AJiEAwIYFoAsBGJBjZwYoQIwFM...
That is not a side point though. It's a major, major difference.