> Advanced users, which need end-to-end encryption and are willing to trade a bit of usability for improved security guarantees, are able to do so by using secret chats

Except when they want to chat with more than one person at once. Telegram does not have any support for encrypted group conversations.

Otherwise a good read. Telegram is not a bad app, but it does not suit my threat model. I'm willing to forgo cloud backups and some usability to have default encryption for all my conversations, which I think is something Signal provides. None of these apps are perfect, it comes down to what combination of trade-offs works best for you.