The two things that help are a) if it isn't too deep, like 4 nested comment threads deep on a three day old thread, then someone may chime in while I'm away and make a similar enough point that when I come back later, I don't anything to say/add, and b) even if no one does say anything, readers aren't dumb. if I say water is wet, but someone responds, calling me an an idiot and that water isn't wet. even if no one chimes in to further respond yes it is and here's why, readers can determine for themselves and decide water is or isn't wet.