Comment by paulryanrogers

Apples and oranges? Let's Encrypt is a bandaid for a (possibly inevitable) architectural weakness, one serving browsers which must communicate with a world of unfamiliar servers. Telegram is a messaging app primarily meant for communicating among people and groups one already knows.

Regardless, using open and verified cryptographic primitives is a best practice for a reason. As are audits. The likelihood any company can start from scratch and produce a flawless solution is a number approaching zero.

I'd feel much more comfortable with something using Signal protocol. Ideally built from independently audited source.