if arguments would have won the debate, and the primary reason to award the win the other way is missing out some debate formality, or detail outside the logic of the argumentation, the arguments mean more.
As you know, this is precisely the kind of interventionist judging I strongly object to. While I do not wish to rehash that debate, I feel far too strongly about this not to raise an objection. This is a bad voting paradigm.
Debaters have an equal opportunity to control the flow of the debate. If one debater loses control of the flow, that's on them. The judge should not simply ignore the debate as it actually unfurled and vote on an argument which, if the flow had gone differently, would've won the debate for the losing debater. That judge's RFD will not reflect the actual debate, but instead the judge's fantasy of how the debate transpired. There is the debate as it actually happened, and then there is the mirage the voter has conjured to align with what they believe ought to have happened.
Voting up debaters based on dropped arguments is denying the reality of the flow of the debate in order to assert some falsehood about how the round transpired ("it was so good I should just ignore that it was dropped"--the "ignore" here is the reshaping of reality, the lie by omission).
Moreover, this mirage-based voting fails to account for the fact that debate is not just (or even primarily) about arguments. As a dynamic and competitive event, it is also about strategy, execution, sportsmanship, and gamesmanship. To vote based on argument quality alone is to flatten the activity to a single dimension and to thus diminish the activity itself. Debate is such a rich event that it is appalling to me that it might be oversimplified in this way.
Suppose, for example, that I faced an opponent with an argument I could not figure out how to beat. Instead of trying to beat it (which I believe would suck up too much character space or research time), I make a strategic decision to focus on destroying every other part of my opponents case in the hopes that I can cause him to drop his own argument. If my opponent drops the argument, but the judge gives them the win anyway on the basis of that argument, the judge is essentially saying that strategic choices do not matter, and thus flattens that debate to a single dimension: argument.
It also irks me deeply that you're only considering fairness from a single point of view. Is it fair to deny a win to a debater who successfully out-strategized an opponent, or who did a better job at controlling the debate? Yes, it seems superficially bothersome to deny a loss to someone on the basis of them not extending an argument, but arguably it was their job to do so. That's what debating is! If you put out arguments, defend them and extend them. Your job as a debater is not to rest on your laurels, but to play the game. On a deeper level then, what you're saying is that it is "unfair" to award losses to debaters who failed to do their jobs, who are lazy or inept or careless or arrogant or erred, etc. Isn't it at least as unfair to the other debater, who controlled the course of the debate better, to award them the loss in spite of the fact that they controlled the course of the debate better?
Your position makes zero sense to me. It's harmfully meddlesome and damaging to the activity, with little to no upside at all.