If you assume that everyone is rational only based on
the points
brought up so far and not their individual thoughts on the issue as a
whole then it may work that way. But it is still groupthink to go
along with the current trend in a conversation just because,
highlighted by sudden switches to other good points that you did not
see at first because you were too busy agreeing with what was said.
If people just agree with whatever the most recent person to speak up
says, then that could be considered groupthink, but accepting that
someone has noticed something you didn't and thus your previous
opinion was incorrect is not groupthink, it's maturity.