I could just as easily publish a crypted link to "invite" someone to
join. As long as they have the link they can "Join" and start posting. The only advantage Stas' method has is that he simply started an advertising campaign for the echo on his own. I suppose that is fine and dandy. Let's see how this takes off. It is far easier for someone to click on that link and see the landing (advertising) page and be encouraged to install Telegram, than it is to install Telegram first and post something to an existing user to wait for approval.
Exactly what I've been trying to get you to see
--- tg BBS v0.6.2
* Origin: Fido by Telegram BBS by Stas Mishchenkov (2:460/58)