In this case, the useful skill is scanning that wall of text to extract the small nugget of useful information:

For small N, finding something in an association list can be faster than finding the same thing in a hash table.

Naggum also could have run some quick bench marks and figured out at what size N hash tables become a better choice (depending on the nature of the keys, etc. etc.), in less time than he spent berating the intelligence of the questioner.