No, I think GP is just aware that the risk of missing a useful dialogue needs to be weighed against the risk of wasting time on a fruitless one.
Proof by contradiction[1] has quite a number of important results. We shouldn't denigrate that machinery.
[1]: https://en.wikipedia.org/wiki/Proof_by_contradiction
""" G. H. Hardy described proof by contradiction as "one of a mathematician's finest weapons", saying "It is a far finer gambit than any chess gambit: a chess player may offer the sacrifice of a pawn or even a piece, but a mathematician offers the game." """
EDIT:
Perhaps this is another skill, related to counterfactual analysis: being able to consider you're wrong just a tiny bit, even if you're certain you're right, just to reaffirm yourself. Holding the two conflicting states in your mind, in parallel, for however brief a moment. Kind of like speculative execution. Doesn't cost much if the other party is an obvious troll, but can pay off handsomely if you somehow ended up with a strong belief based on badly flawed assumptions.
That’s a strawman. Not being willing to entertain every prospective interlocutor with (as in the upthread poster’s specific example) flat-earth theories is not the same as assuming everyone who disagrees with you is a hardcore believer of some really stupid thing.
I imagine you might dispute that that ever happens to you, and it may be that you are so thoroughly rational that it doesn't. But let me suggest a counterfactual for you: imagine you are not as rational as all that. How would you know? You would never engage in the conversations which would demonstrate this. So, as a general principle, maybe you should not assume that you are.