You are right mate, the signature campaign is not their only way to promote the brand but if you open the site then you will also know that wolf.bet also has an affiliate program that can actually be used as a promotion on various websites.
Meanwhile, I see no indication that the wolf.bet campaign requires a lot of participants from various ranks. It is possible that the manager and site owner are satisfied with the performance of the actual participants who are the best participants chosen from a strict selection. At the moment the campaign has 30 participants from two rank (Hero and Legendary) with an average number of weekly posts over the past 3 weeks is 771.6 posts spread throughout the forum as I can see in the campaign spreadsheet.