They are many user out there still doing that kind of habits, but in bounties board only, in the global board such meta beginners and help then there are many newbies or users here in our community who are improving a lot such us they contributed very well and then earn some rewards and ad we can see there are many newbies who have earn a lot of achievements because of their contribution. But we can bot deny that there are also a lot of newbies don't care thier account as long as they can make a post.
The newbie was working in the bounty now with the Facebook or Twitter accounts in the Facebook or Twitter campaign.So forum now the working platform for the new people to the forum.If the newbie made the good posts,they easily update their rank to the high rank and had an opportunity to work in the Signature campaign.But some new people come to forum and they try to miss use of the platform by multiple accounts.The forum give us the chance of earning opportunity,So it should be used wisely and no miss use of the chance in the community.If the newbie not made post longer it became the inactive account and became useless.If the newbie contributed to the community,they get rewarded for the same.
In short some newbies didn't think how to rank up cause all they want to do is to earn small amount of money from bounties and we can not deny the fact that some newbies prefer to joins bounties rather than making good and quality post in order to reach milestones here in our community and like what you said above mate that they can also earn money through signature campaign if thier rank is eligible for it.
In my own I think those accounts participating in bounties are some of them are in one hand, maybe some people have multiple accounts in thier cause you imagine how small the payment is if you are working on it so there's a possibility that they created multiple accounts so that they can join and earn much bigger amount.