I'd like to point out that this uses important improvements over the naive Ziuba's strawman version: memoization and callbacks using the event loop. The callbacks improve concurrency, allowing a single process/thread to multitask requests, and memoization reduces total time spent per request.

Actually, if the async lib memoization facility shares values between requests, which seems quite sure to me, all requests but the first one are served from its cache in the test the author uses as example. This still doesn't highlight any strength of node.js IMO, asides from the easy shared memoization. It could be translated to Tornado-web, an async Python framework, almost literally.