E2EE is genuinely hard to implement in the context of a chat service with server-side chat history, large (10k+ user) group chats, and multiple clients (including web applications).
I'd flip that around and say that server-side chat history, large group chats and multiple clients are hard to implement in the context of an E2EE chat service. What I mean by that is: E2EE is a necessity, not some nice-to-have feature.
Building a chat service with server-side chat history but without E2EE is like building a car with very nice headlights that doesn't actually move.
Signal chat history is client-side. You have to explicitly "back up" and "restore" messages to move to a new device, and if you lose your phone, your chat history is gone forever.
And again, Telegram __does__ have e2e 1-to-1 secret chats. It's just that the group chats do not. This doesn't stop you from starting a secret chat with each and every person you'd like to chat with e2e.
As far as I know, one-on-one chats are not E2EE by default (there's a "secret chat" opt-in) and group chats cannot be encrypted at all. Has that changed?
Not supporting E2EE (cite: Telegram is not E2EE) and E2EE being not on by default are two very different things.
Not being on by default has an impact on other things, that the users value more. If they were on by default, they would lose it and Telegram would lose part of its appeal. This way, users themselves can choose the trade-off they are happy with.
> People value that other functionality more. You may not like it, but that's how they are.
I've once listened to a presentation given by someone from the company behind AdBlock Plus. They were explaining their (back then) new "Acceptable Ads" program and how an overwhelming amount of users chose to let the program enabled.
They even had a pie chart showing over 90% participation in the acceptable ads program and interpreted it as user choice. ("That's how they are")
After the presentation I asked whether they've tested how many users actively enable Acceptable Ads participation in the settings if it's off by default. To noones surprise they did not run such a test.
Not changing the defaults should not be interpreted as user choice if the same settings end-state is not reproducible with other defaults.
Usually any default, no matter how hostile, stays set. The reality is that users can be nudged easily and rarely ever change any settings at all.
It's bothersome that you don't admit that your false statement was false and continue to double down with irrelevant discussion. Telegram has E2EE therefore you are wrong.
"Telegram is not E2EE" is factually incorrect.
WhatsApp has E2EE however it ships your private keys to cloud storage by default. So it's even less secure than Telegram.