As a non D&Der I am wondering if they really belong in dialogue at all
They do but in the case of D&D they exist for a specific purpose.
As in if you fail a dialogue roll (which you do once. Not many times for the same thing) you in essence unlock a new "path" in the story. Because in a tabletop game the outcome is rather flexible. The DM can have a set story in mind, or be more freeform with a general idea of where things should go but letting the players decide how they get there. Helping and setting things up for them along the way.
So a failed roll can lead to an entirely different story path than the one that comes with a success.
The issue here is this is a video game, and in a video game all paths are set in stone. We know what the outcomes are and failing a roll doesn't lead to new path entirely (that'd be too much work) or gains any benefits that you'd usually see in a typical game of D&D. As there the DM will try to make things interesting, some DMs will even just go "Well they are off the success roll by 1... I'll say they succeeded because that makes things more interesting" without the players knowledge. Since the focus is player enjoyment and a good flow to things rather than frustration.
As far as I'm aware there are no failed rolls that lead to a path of their own, once again for good reason since that's insanely costly to build around. And in many cases just feel like failures instead of new opportunities. The failures in dialogue rolls aren't fun because they are failures or of the difficulty but because of the story they build and the new forks they make in the path of the story.
A video game will naturally lack this. And so does BG3. So yeah rolling for dialogue has a place in D&D but not in a video game adaptation of it.
