There is no need to make multiple threads on the same topic. You are annoyed that there are multiple topics about Black Cleaver. However, by making multiple threads on why it isn't OP, you are doing the exact same thing that annoys you so much. I also hate the multiple threads about an overpowered item, but at least they are all made by different members. Pretty much what I'm saying is keep things in one thread.
Besides, by making multiple threads, you are weakening your argument since the thread starter loses all credibility if s/he felt the need to make multiple threads within a short amount of time about it. It's like a little child screaming and yelling until he gets what he wants.
Who are people more likely to listen to? The veteran player who is considered one of the best players in Dominion who calmly presents data and draws a conclusion from it (which is what Sauron did) or the random player whom none of us really know telling us how we're all wrong. Then calls us terrible players, don't know how to play properly, and are acting like children because we disagree with him?
Make one well developed thread, if people don't agree, you move on since what you're saying is falling on deaf ears. By making multiple threads, you are wasting our time. More importantly, you are wasting your own time. If people are still complaining by the next patch, you "bump" your thread to bring it back to the front page.
Eventually people will start testing what you say, perhaps to just prove your wrong, but they may find out that you're correct. Not saying that you are correct, but this is the way you should go about changing people's minds.
You make a second thread when your original thread if closed and a SIGNIFICANT amount of time has passed and people are still complaining about it HEAVILY.
As to the people who are complaining about it, the same logic applies. Make one thread that is very popular and active about the overpowered item, then it makes Nome's job much easier.
Nome: "I'm going to browse the Dominion forum to see what I can do to help Dominion out...oh, this thread has 10+ pages. I wonder what's the problem here. [reads about BFT and BC]. Oh...I got some work to do.
One big thread sticks out and makes Nome more likely to read it. Having multiple single page threads talking about the same thing surprisingly might make it less likely for Nome to read it since he might think it is not a huge issue. I am talking in a general case. If BC is as OP as you guys claim to be, I think Nome figured it out by now. If he didn't...he'll find out the next time he logs into the DominateDominion chat.