It’s a bit disingenuous to say that Signal has nothing to share. Signal has access logs as well as metadata about the phone number, the name given on the app, group memberships, etc.

With Signal, it’s also trivial to find out if someone is using it by adding their number to one’s address book. Then they can ask Signal for access and other information. That’s not easily possible with Telegram (there are settings to prevent this).

That said, Telegram does store all non-secret chats in an accessible form (for it) on its servers.