I agree that it can get annoying sometimes when the smae old topics come up again and again, and I admit that I have said to myself on a number of occasions "not that ol' chestnut AGAIN"! But there are new people coming to the site all the time, like Kimmi says, they can give new and fresh input to a previously discussed topic.
Sometimes people don't feel comfortable to post in the original discussion, particularly if you disagree with the general flow - it can be a lonely old place out there on your own little limb! But the topic eats at them, they know they have a point to make, they know they think differently, and then bingo, before you can say Geekmolian, their fingers have typed a new thread raising the debate again because they want to be heard now!
While it may be frustrating that we find the old topics coming up again and again, if you feel that you have said all you can say on a subject then let someone else do the talking!!! I learn all the time off this site, even topics that have been raised before. Let's face it nearly every topic you can imagine has been discussed on here, so The Nail Geek would become a search facility and not a forum ... and I'd miss a good old chinwag, debate, a laugh and a tear with me good ol' Geeky mates.
Like Angie says, a little tolerance is needed.