Thing with telegram groups is, not everyone has an account on telegram, mostly cause you need to give your mobile number to register on Telegram and that doesn't align with the motive of using crypto
For what reason you really don't want to use any telegram account because you give your mobile number? What is the privacy that stored on your mobile number? Exactly nothing, I'm not minded to use my mobile number to register.
You might not mind but there's a lot of people who do. Many people do not want to give their mobile number to random services and value their privacy. THe entire point of bitcoin was creating a service not controlled or monitored by anyone so sharing your phone number plays into that