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?
I think the average gambling site avoids excessive spam on telegram...
I see discord is much cleaner than telegram. Telegram is very easy to penetrate scammer and does not have good filtering when compared to discord.