I have noticed that a curious and behaviorally contradictory thing happens when critical mass of opinion starts to form, of the belief that a thread has veered off in a direction that people don't like or don't want to pursue.

Instead of letting it go and saying nothing, people begin to leave posts that say things such as:

<font color="purple">
I think we should let this go

Let it rest

I don't want to keep this going BUT </font> followed by the person's thought -- as if well, I'm gonna post my thoughts but I wanna have the last word.

My suggestion would be not to post. Not to say let's close it down, or I agree it should be closed down or anything at all. Because that's what ending the thread means.

And yes, I have practiced this, even on a thread or two that I have started after they turned bad on me, like naughty children who refused to obey me. I simply stopped participating. It's always an option, and like depriving fire of oxygen, it ends the thread more effectively than continued pleas for others to stop posting (but not, of course, you).