Anti-spam?
All sign-ups require approval which means that new sign-ups don’t appear until they’ve been approved.
All approved members are able to invite a (limited) number of new members each day. These (I believe) are treated as more likely credible and valuable members of the community and get approved more quickly.
The moderation facilities in Discourse will give you a hard-on, @pap .
You have a separate moderation in-box and all moderation activities are queued up for you.
See here (Also note dark theme banner at the top)…
Amazingly, @barry-sanchez is no stranger to the moderation queue.
Flagged posts - off-topic, spam, inappropriate, etc are there as are new sign-up approvals, users moving between trust-levels, etc.
They are all presented in a shared queue so that all moderators can action them quickly and easily.
Remember too that moderation rights can be earned on Discourse by moving up the trust levels by being a regular and valued member of the community (regular visits, reading, contributing, voting, receiving votes).
All moderation history is also stored so everything can be traced. Any moderator activities that impact a post appear in the post to show, transparently, exactly what has happened.
See that this topic was closed and then re-opened…