That's not necessarily correct. If you leave something standing without gainsaying it there is a substantial fraction of the viewers of the interaction who will come away with the impression that that party that did not speak up against the last comment lost the discussion because they ran out of arguments. This is so widespread that there are multiple names for the phenomenon and lots of good interaction has been ruined by it.

Obviously I don’t claim to speak for everyone else when I say it only seems that way to him. I’m being tongue in cheek. But I do think it’s the wrong instinct and the fact that some people agree isn’t reason to give into it.