I’m a mod in several 3D printer forums, and have been dealing with spam and spammers for a long time. New user limits are a good thing, and should include preventing off site links. The ones I’ve seen usually have both a time and post count expiration.
They’re a real pain for honest users, but a major tool in limiting spammer problems. Just look at all the unmonitored forums that have been taken over by spammers. They don’t care if anybody actually reads the posts since they’re aimed at boosting search engine rankings (aka SEO). You can hire a poorly paid 3rd world person (India and Pakistan are popular sources) to register (bypassing the bot checks), wait out any time/post limits, and spam away pretty cheap. Some of them are pretty good at finding configuration holes (last one i really with was anonymous users could flag posts, exploited to post offshore Viagra seller links).
Hope it’s a while until they find this one. We’ve had days where we deleted well over a hundred posts on a Google SEO listed forum where I’m one of the moderators. Don’t be too quick to turn down the new user limits