I'm moderating one small Discourse forum and we, like everyone else, get spammers from time to time. Our forum is small, like 40-60 weekly unique visitors. Our forum requires that each new user's first post must be reviewed by a moderator before it appears and this catches most of the spammers.
Recently we've been getting spammers posting to some older thread without contributing anything new, like writing:
"Thank you. This solved my problem." While posts like these are suspicious, a moderator can't block them outright because they aren't against any rules and they might be coming from a legit user who has just created an account in order to thank someone for helping them out.
Usually after their first post is published, the spammers come back a day or two later and they either make a new post or they edit their previous post to include "hidden links", like:
Thank you[.](https://www.SomeRandomSpamURL.com/) This solved my problem[.](https://www.SomeOtherRandomSpamURL.com/) [.](https://www.EvenMoreRandomSpamURLs.com/))
I'm simply curious as to why would someone do this? I understand the purpose of regular spam links where the spammer tries to explicitly divert traffic to some site, but if the link is hidden behind a dot, then 99% of users likely won't ever realize there's a link to be clicked. If they do, then they'll likely realize it's a scam link. It's also not like someone could accidentally hit a dot on a forum post either.
What are these spammers trying to gain by creating these "hidden" spam links?