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.
Yes, Those who do this want to promote their projects quickly by marketing them, but the marketing systems are different in this forum, so they cannot stay here for a long time. Other projects running on the forum for a long time are extensive projects with no problem marketing to several sectors. Due to this, they continue to promote this forum for a long time, which increases the visibility of their project.