why don't you see a spammer at a higher rank, and bully him too? Don't you think, a high rank account with a lot of merit will not produce multi-account users or spam workers to join the prize campaign? In fact it is higher than the income of a Newbie account spammer.
You mix two different problems with each other: spamming and account farming. Spam, which by the way is most often manifested in the terrible quality of posts, and not in their huge number, comes mainly from the newbie rank participants. Spammers are those who don`t understand the subject at the proper level, so they write silly, useless comments, just to fulfill bounty quota. Therefore, no one says that only newbies are spammers, or that all newbies are necessarily spammers. Members of higher ranks may also suffer from this disease. But most often spam comes from newbies, as they aren`t familiar enough with the rules of the forum, and throw their strength to get easy money from signature campaigns.
Account farms, in turn, can be created by anyone, regardless of rank. The fact that a person has alternative accounts and with their help participates in bounty campaigns doesn`t mean that he`s a spammer, since he can write high-quality and constructive posts from all his accounts. Another issue is that these people also violate forum rules, but they do it in a different way than spammers. The apogee of these two problems are members of the forum, which combine the features of spammers and account farmers. They become the main reason for widespread violation of the rules, and cause a huge wave of dissatisfaction and irritation of forum participants seeking to follow the original goals of this site.