WhatsApp does that too now, even on the web.

Signal has a desktop client as well (no web one, unfortunately) – I also haven't seen any hiccups there.

Yes, this is 10 or 100 times more complicated to get right when using end-to-end encryption, but it's clearly doable, and Telegram has finally been proven wrong empirically about there being a dilemma of security vs. usability in messaging.

Yes, they still lead the field in usability, but the encrypted competition is past the hard cryptographic hurdles, allowing them to focus on the front end.