Wasn't the point of the original post that node.js blocks the event loop while it executes functions and thus effectively kills concurrency? Not how fast it calculates fibonacci numbers and sends it over http...
The point was that it kills parallelism – Node is just a single-threaded event loop, running on a single core. And since computing fibonacci numbers is a CPU bound activity, that type of benchmark would be relevant but for the memoization bit.
EDIT: Well also, the author would have to actually benchmark this vs. Node with many concurrent clients in order for it to be relevant; here he's just timing a single request from start to finish, which obviously doesn't say anything about how this scales.