You seem to make it sound like it is a small fringe group. When really this is more of a casual thing of people taking it upon themselves to be the mods of certain threads they see fit. Whether it be syntax correction or telling OPs that they should use the search engine on questions that are outdated in a good number of cases, and thus flaming the OP. Or just flaming and trolling all those who are actually contributing. I do think the report button should be used to clean this problem up
Also if I'm taking what you say out of context sorry.
In terms of the number of members, it is a fairly small problem. If the problems are minor ones the best policy is still just to ignore the repeated offenders. It really is the case on the internet that if you ignore trolls then they'll go away, and the really persistent ones will eventually leave or get banned.
If people really are doing daft things like making duplicate threads (let's face it, how many "what's your favourite drift car?" or "how do I get gold chrome?" threads do we
really need? Simple searches would handle a lot of queries - they can only be a certain level of dated on a game that's
less than a year old... 
) or if someone has major spelling, punctuation and grammar issues then it's fair enough people calling them out on it.
One of the ironies of course is that a lot of the members for whom English is only a second language and for whom the rules we have are intended to assist, use better English in their posting than many of the native speakers
A small level of self-moderation or user "assistance" can also save the moderators having to clean up hundreds of problems that wouldn't have happened if people had read the AUP in the first place. I agree that some users take it too far though, to the point where they're no longer contributing to the forums.
The other thing is of course that the vast majority of these problems happen in the GT5 section of the forum, where - without wishing to offend anyone - there is generally a much greater concentration of less mature users, a much greater number of posts, and things are more likely to get out of hand. Again, the mods have plenty of genuine problems to deal with (swearing, racism, flame wars etc) making the odd pedantic git less of a priority.
While I do agree, it's only worked about 25% of the time for me.
Moderators are able to look at a situation from the outside and see whether it's worth acting on. To you it appears they may only be effective a quarter of the time, but it may well be that only a quarter of what you think is a big problem might actually be a problem.
Also, since moderators don't reveal when someone has received an infraction or not, how are you sure that nothing is being done 75% of the time?
