Google is seeking the single best answer to a direct query from an effectively infinite number of data points… For most queries there is one right answer that Google will return to anyone who searches for the term in question. In short, the data set is infinite (which means no human is capable of doing the job), but the target is finite. Facebook, on the other hand, creates a unique news feed for all of its 1.44 billion users… what is infinite are the number of targets.
When the data set is big (Google’s challenge) or the user set is big (Facebook’s challenge), you need an algorithm. Good article, in large part due to good insights from Ben.