The article holds up Netflix as a shining example of movie recommendation engines but Netflix has only 3000 to 5000 distinct movie titles (depending on your country). You cannot get interesting or surprising movie recommendations from such a small search space. Imagine the extreme case where Netflix had 1 single movie, say "Twilight". They'd always recommend "Twilight" even if Donald Knuth wrote their recommendation engine.

You need something like IMDb's catalog of 500,000 movie titles to do something interesting.