I disagree that one campaign is the reason why new ones don't appear, although I didn't keep track of how many new campaigns a week or a month appeared. People are always looking for the easiest and the highest-paid signature campaigns, and one that you mentioned offers them just that. The fact that anyone can apply, that there is no selection process and that number of post is 20 per day provides a solid income opportunity, especially for those who have multiple accounts.

On the one hand, it is not good that some spammers have switched from bounty to signature campaigns, now they are all over the forum despite efforts to prevent them, but maybe some of them will see good opportunity and try to contribute to the forum more than usual.