Sure.
Telegram uses encryption that allows themselves to read your messages. This shortcut allows them to restore messages, outside of secret chats, when you install the app on a new device. It also makes distribution of your messages to large groups much easier for themselves.
Another shortcut Telegram took was to hide your phone number only when it wasn't in the contacts already. There are a limited number of possible phone numbers, so discovering a "hidden" one is possible.
Telegram lies about privacy and security the same exact way that Facebook does!
More people need to understand this before recommending any messenger app.
This is a fairly easy answer. Signal refuses to take shortcuts that others are happy to use.
You may find this virtuous, but I'll argue that it isn't.
It's much better to start by having windows that don't lock than to keep holes in your walls all year while waiting for windows that are insulated, lockable and can be cleaned from the inside.
Signal leaves the holes until they finish the insulated window that also creates electricity.
That's a fair criticism. I prefer using Session with better multiple device support and without waiting for Signal to finally stop using phone numbers.
When using either, disappearing messages should be enabled.
The part about PFS falls down, for me, when you assume both that keys can be cracked in some shorter than normal time-frame, and that the new key (per message, or less often) won't also be cracked quickly.
I could have guessed that you used Android before your previous message simply by your positive impression.
Try switching the OS and keeping your messages then you will discover the difficulty. It's worse if you began on iOS.
I just recently had the Signal servers silently stop communicating with the app. I had to create a debug log to find that the server was sending an error for some reason when it was working the previous day. Switching apps was the only solution remaining.
Signal fails as a useful solution as long as:
- I can't switch devices and keep messages.
- I must give them a phone number.
- Multiple devices can't cooperate to allow me to chat continuously from any device.
- Messages can't be sent/received arbitrarily because the server decided my client isn't acceptable.
Signal is not reliable and very user-hostile.
I think most iOS users have no trouble understanding how user hostile Signal has been after getting a new device or losing all the messages they wanted to save.
As for the user base, that's a problem that fixes itself as more people switch away from Signal.
Another shortcut Telegram took has to do with the default settings they chose.
Rather than defaulting to using secret chats, they chose to default to not secret chats for every new discussion and group. This isn't in the users' best interests, so Signal encrypted everything and doesn't offer non-secret chatting.
Regarding SMS, Signal had made this mistake for a while too, because they chose to drop encrypted SMS, then dropped SMS entirely later. Signal let perfect be the enemy of good.