It's their business and they're the ones that should take full responsibility and on how they'll make those customers that are attracted by the manager, maintaining them is already out of scope by the manager.
Simply example, why famous brands use artists when advertising their products? There are three important points I can mention, these are just a few and there are many others.
- Fame
- Target customers' trust in the artist
- Network
In this forum, who is the artist? he/she Reputable Admin, Staff, Mod and BM/CM. By using BM that has a good reputation, then
- Forum users put their trust in the casinos supported by BM.
- The fame of BM who has a good reputation
- User attention
All of this is sufficient reason why the project uses the services of a reputable BM for its advertising here.
It's all about the promotion and the target market and they see that it's appropriate for them to use it. Just as you've said, like the traditional way of promoting, BMs do help to make things set for the new casinos that will hire them.