There are restrictions on what you can place in your SIG space based on your rank. Most campaigns do not accept Newbie, and only a few accept JR. Member; so atleast now it does take a while for new users to achieve a rank to join a campaign.
Not that it's a bad idea, but the Forum leans more towards less regulation and allows the community to sort it out.
There are so many users who post content that have nothing to do with the topic.
The best thing to do is use the report to moderator button to get the post deleted. Most of these garbage posters do the bare minimum and even one post getting deleted can wipe out their pay, hopefully to the point they leave, or turn around their membership habits.(Not holding my breathe on the latter)
Here is a
guide to reporting that is useful.