I think there are plenty for every casino since each player can play in different casinos, now it is up to the casino on how they will maintain their player, and I think Metawin is pretty great on that. They have frequent email and notifications, they even remind player about the duration of the game . They even sent a last-minute notice to players if the tournament, giveaway or bonus is about to end. They are very active in keeping in touch with their player and that is a great thing since with these kinds of attachments to player, it is very hard to miss or not know about their events.
Bigger sites than Metawin like Stake etc continue advertising their services within this forum and aren't showing signs of stopping anytime soon.
True that, the forum is a place where the majority of crypto enthusiasts meet, even anti-crypto also flocks to this forum. So if one wants to advertise, this forum is a great place due to the different kinds of people interacting in this forum.