As much as I love free software, I also need to consider how to make things more active.
We can have IRC, Matrix, Mastodon, Diaspora, etc. But the last two Debian meetups I hosted nobody from this mailing list showed up. So we are talking about an empty audience. And worse: during the events, nobody was using Debian in their laptops (me included).
And everything is definitely mobile nowadays. Telegram isn't an attempt to hijack this mailing list or any other communication media, but to increase the possibilities. Even for newcomers.
BTW I use the free software client named "plus" to access Telegram.