The advantage of telegram is that they can directly answer the issue or concerns if the team are online. Here in this forum, it takes a minute before they can answer and very strict about the rules. That's why most of the team prefer to answer on the telegram or other social site.
Personally, we did not like telegrams, but at the request of investors, we opened chats there. Urgent questions can always be set there.
And aside from that huge volume of spammers are in telegram, and most of them are adding bots too. Anyway, it is still important to have a telegram channel because some investors are comfortable to use it as a mean of fast communications.