I don't see any obvious absurdity about saying "suppose problem A only resolved by elven magic; then what would happen to problems B, C, and D?".

I do see an obvious incoherence. Xyrik's scenario was;

a hypothetical situation in which everyone on the planet decides to temporarily get rid of the concept of money or currency, and pool our collective resources and ideas without worrying about who owes who

This is a highly complex scenario, made apparently simple because the complexity is hidden inside the words. What is the problem A that is the only thing hypothetically solved? The "get rid of the concept of money or currency", the "pooling collective resources and ideas", the "without worrying about who owes who". What do these look like -- what do you see if you follow a few people around in the hypothetical world? What do these phrases mean, to be able to say, these things B, C, and D are not part of that? How can you say what would happen to them, without any description of what the elven magic actually did to produce something described by A?

The scenario is too vague for these questions to be answered.