No, asking those who are arguing to go to site mail may not work but what is there to lose by trying?

There is nothing wrong with legimitiamate debate.  However, we either have those who deliberately start thread with the aim of starting an arguement or those who just will not stop.  If a mod drops a warning into a thread, it's like a red flag to a bull. 

It's either take it site mail, drop it, or end up with every thread locked by the mods.