Telegram is one of the most popular messaging tools, chosen by many online services to stay connected with their audiences. Major shadow libraries Z-Library and Anna’s Archive used Telegram until this week, when both accounts were terminated for copyright infringement. While these websites offer infringing content, both were cautious to avoid copyright troubles on Telegram.
Euh it is still to young IMO. And NOT user friendly, you pretty much need to self host or it is very centralized in the way it works. Which is partially due to it not having many users yet.