It used to be like that, but now the caps for those pay-per-post campaigns are much lower than before.
For example, the cap for PD sig payment was 2.4 btc per month and it is now just 400 posts per month.
And IIRC, Stunna said the campaign will no longer be pay-per-post next period.
0.4 BTC per month for full members is still a lot for simply posting on a forum; no other online community does that. Besides, it's very hard to post more than 400 constructive posts per month, those who made more than that are likely to have included a considerable number of unconstructive posts.