My theory is that the recreance was really a peace treaty between the KR and the parishendi.
We know the radiants gave up their surges willingly, and that the parishendi chose dullform on purpose as well. The result? A complete stop to their war.
With that in mind, that might be why lots of people are so obsessed about surgebinders returning. It means that both sides will have to bond with spren again to survive. Bringing an inevitable war.
As far as the one order that remained at great expense to the others, one group does seem to have soulcasters, which is a surge. We've already seen two fake soulcaster devices. What if they are all fake? We've been told again and again that the war couldn't continue without soulcasters. Its propping up the conflict. It might just be the last order of KR trying to wipe out the last of the voidbringers. Since they aren't using their powers directly, it might not elicit the same response from the parishendi. In fact they didn't agree to try stormform until a surgebinder showed himself on the battlefield.
