My thoughts on this subject were more towards rewarding users for reaching a certain level vs being able to come right in and join the campaigns. First of all, users need to learn about bitcoin and the forum before they pop in to come earn.
I don't think it is the administrations place to say who can and cannot earn money, especially if they are not doing anything on the forum except making a post in a specific section not designed for actual discussion.
There is a reason why the people behind ICOs want broad exposure on social media -- because they want many people to see posts (that are really advertisements) for their ICO, and hopefully have one of their #hashtags go trending for some people. I would not be surprised if some of the mass accounts are actually hired by the people behind the ICO to manipulate social media, and the other mass accounts are still providing social media exposure to the ICOs anyway, so those behind the ICOs usually wont care one "person" (more likely a bot) is claiming their bounty 100 times.
Regardless of the above, I don't see why someone who isn't very active on the forum but is active on other social media platforms shouldn't be able to participate in bounties. If someone wants to tweet about ICOs or talk about ICOs with their friends on Facebook, let them, and let them earn money doing so. If we force people to rank up to participate in bounties who have no real interest in posting here, they will only post crap they put little effort into, and will go around begging for merit so they can rank up. If they have no interest in posting here, let them post what they want on social media.
Paying for signatures is a little different. I wouldn't agree that the merit system could be removed if signatures would be put behind a paywall either. I think the merit system is a pretty good system, regardless if there's other limitations on signatures or not. Its not perfect by all means. However, those that haven't earned any merit since the introduction of the system are fairly easy to spot. I've also supported hilariousandco's suggestion of a pay for signature type system in the past. I think it would be mostly beneficial. Of course, the price of this would need to be carefully considered. Too low, and users won't care about spamming, and getting banned, because they'll likely earn their investment back before they get caught, and they'll just reinvest on another account. Too high, and your just pricing out legitimate users out of the usage of a signature. Several users like to link to their personal projects within their signature, and other interesting projects by others. We shouldn't be removing the ability of users to do this. I'm not 100% for the idea of a paid signature, and don't see it as the best solution, but more of a compromise due to something needed done about the issues.
When you charge people to enable signatures, people will quickly learn they will lose their investment if they post nonsense. More effort could be put into banning multi-accounters when they are posting crap, and maybe even the threshold to ban them should be lower, so someone with 10 accounts might risk $200 instead of $20 if they post even a little bit of low quality posts.
Non paying users might be able to have very basic signature functionality. Maybe users could have some signature features enabled for free if they self-certify their signature is not being used for commercial purposes each time they change their signature, and if they are caught with a commercial signature after certifying their signature is not commercial, their signature privileges can be revoked for a year, or however long.