I haven't seen any Gamblig Platform who used Telegram for Promotions, most I know is that they use Discord.
Do you have any Idea why they don't have any Telegram Communities? and why does it seem they don't use this platform for their promotions?
Discord is better and it's build for players and gamers and gambling sites has a lot of gamer members I like Discord features better than Telegram because you can create sub topics and sub categories, and besides telegram is very much associated to Cryptocurrency projects.