What we can do is to have a requirement after creating a new account for users to be able to post links, which means that if someone creates a new account, they shouldn't be able to post links unless they spend a specific amount of time in the forum like 24 hours or something. So if someone joins the forum being interested in the forum itself and plans to stay, they should be okay because they will have the requirement completed within a few days, and those who are doing these things won't be able to post links to promote specific services.
How is this going to stop them?
They will just create the account, wait for 24 hours make the post and be done with, it might deter your lonely manual copy-paste spammer that just wants to post as many ref links on as many websites as possible but it won't do much if some service really wants to spam the forum!
As soon as they learn that there is 24h delay they will adapt accordingly!
No more newbie jail so if you see something bad from newbie posters, report it.
Newbie jail has nothing to do with this, newbies still can't post images so what's the difference in restrictions?