Should Merits and signature campaign be the only cheer to have interest and feel satisfied with the forum alone, I've seen many members not having enough Merits and have been active on the forum, while some have also been very active and nit interested in participating in a signatory campaign, i think what needed to first define is your purpose for coming, this will now determines what you are after and how you can get it fulfilled, so don't tell me those not in a signature campaign or not having Merits got their immune weak on the forum by being timid or got inferior, but i think everyone likes the way he has found himself here since each user determines his fate all by himself here on bitcointalk.
You are right on that because I have also seen many posters not having signature campaign on them or applying either. For those users it doesn't matter what financial gains from the forum yet they are dedicated to the forum, supporting other users were necessary. So I think the main benefit or booster is the learning process that the forum affords. It trains people's mind to investment in bitcoin and cryptocurrency it also expose users to the reality that online space is to be taken with all care and diligent not to be scammed.