Oh, I just realized that I haven't saw their signatures for a while and that their previous campaign was closed. I agree with others that they barely can attract good posters with such low payment rates. Especially if you're in their lower tier. But where did you get that you can earn up to $40 week? I see that in tier A they pay 3500 Satoshi per post, it's almot $1 and if you will make 60 posts, you can earn $60.
But allowing to make up to 60 posts, damn, it leads to spam. I don't see how someone can make so many quality posts in just 1 week, especially considering that most of these users probably weren't accepted into higher paying campaigns. And we should expect that users will try to reach max allowed quota to maximize their earnings.