Say your characters are standing before the moss-draped opening of a dark, gloomy cave, and they’re deciding whether or not to go in.
You know they need to, because there’s a glimmering, all-powerful gem in that cave they need to find (as well as a nine-legged creature with slobbery fangs and poison barbs guarding it.) The question is, how do they get into the cave?
Character A saying, “Let’s go in” and Characters B and C nodding and saying, “Sure, that sounds good” might get them through the door, but it doesn’t lend much by way of excitement — or character development.
Agreeing, in fiction, isn’t nearly as exciting as disagreeing.