I have seen many of the telegram base casinos. Even when I was a Member I saw some of them here and they were doing well in the telegram so this is not the first one for me. Betfury was also using telegram but I don't know for now.
One thing I discovered from those telegram casinos which launched their signature campaign in the forum has not really stay long except Betfury.
Each platform has its own marketing or promotional plan. In this case, there are many casinos that reduce promotional activities on the bitcointalk forum and increase them elsewhere. Moreover, many casinos have budget issues.
I myself have managed the signature campaign of a Telegram-based casino. What I have observed while managing this is that most of them expect that, since they are investing a large amount here, they will probably get huge traffic from here. And many do not even understand that signature campaigns are not just for gaining traffic, but for building a long-term brand. And this is why many of them don't keep signature campaigns running on this forum for a long time, they focus more on other promotional activities.