There are times when a PM might resolve a forum issue rather then going the other measure of using the warning/infraction system. It's up to the moderator depending on what the issue was.
I'm not really going to comment to much on this thread.
Cricket might give me another infraction.
All forums have a suggestions/feedback or some sort of section to ask questions for the admin or mod's to reply to. People need to use that chance to ask questions about the forum rules in certain categories to be sure they do things right.
Joining the forum and first post clearly violates the forum rules doesn't make the moderators happy as they know from the get go that the member had no intention of reading the rules. Makes it a little more easy to issue a real warning if it happens with the next couple of posts.
If people would follow the forums rules from the start and bite there tongue sometimes and not reply to certain posts, they wouldn't run into problems with that forums moderators which could lead to a infraction for themself as well. The report post feature is there to notify the moderators to investigate or to remove spam. Don't reply to the spammer because that wouldn't make a moderator happy.