I'd disagree with this opinion. Dialogues do play important part.
You are to free hostage. You have options to force the fight, or ask for help a party member. Then Varrick tells a lie, that the boy taken hostage is lost son of Viscount, and if something will be done to the boy, Viscount will have revenge. No fight, everything solved.
Or a quest, where you exit cave after certain encounter with Merril and clan keeper, and you meet horde of angry elves. With your dialogue options you can either cause the fight and wipe the elves or solve it peacefully.
They also have influence of what party members think about you, and how they will choose during main story line.
Also decisions you pick in dialogue options, even in side quests will bite you in the ass in act 3![]()
The only thing that has bothered me about the dialogue choices and party reactions, is I will sometimes choose an option, or a path only to have some negative respect (I'll call it) from a party member when there was no indication that would happen.