[kelthuzad]

>People also aren't aware that phone numbers and usernames are tied on Telegram.

But you can, under Privacy & Security, switch Phone number visibility to "nobody". You can also change your username anytime you want to. A new feature called "anonymous numbers" allows you to purchase and use virtual numbers (they start with +888).

I think the bigger problem here is that Telegram has not e2e encryption enabled by default, which is definitely suspect.