Depends on the topic. On bigger forums there are specific questions that get asked in a new topic by a new user once a month or so. That new member should likely search a little, maybe even before they join. Posting the single word "welcome" in a meaningless intro topic by someone no one else knows or cares about is annoying but should it be legislated against? Probably not.There is a natural tension between using a necro thread vs posting a new one to have a helpful member say "there's already a thread on that".
Over on INGO, intro threads are locked after a few days. Keeps newbs from running to 50.Maybe say, or strongly suggest, if you necro bump 25 or more of the year plus old intro threads you will never get access to the classifieds?
One noob can do some serious necro damage in a few minutes completely juggling up the new posts sections we all go thru to get up to date.
Right up there with the daily bumping for months of for sa lo e ads but you can block those guys since they are just here to sell over priced or unwanted stuff with wierd stipulations.
Just a thought.