I see what you're saying: opposing arguments should not be parsed from a presumption of falsity, which amounts to writing the bottom line and working backwards from there. Which is quite true as far as it goes. But it seems to me that your proposal contains an implicit bias in the opposite direction: by placing situations where the opposing argument is valid above all disagreements but on the same scale, you're privileging concordance relative to dispute.

Now, I suppose you could argue for doing that consciously, on the grounds that people generally find it difficult or embarrassing to update based on their opponents' positions and need all the help they can get. But doing so would strictly be a psychological hack, so I don't think we should be arguing for it on rationality grounds.