[gersh]

Monopoly search is bad because it is easier to game. People have gotten so good at manipulating Google rankings, that there is room for competition. Merely being small has some inherent advantages. Being bigger and more popular can be inherently bad.

[gentschev]

Yeah, I think of it as the Google uncertainty principle (after Heisenberg). As soon as Google measures a search signal, just the fact that it goes into the rankings means that it degrades in quality. People start reverse engineering the ranking and trying to game it. So it's kind of an arms race between Google and the text ad industry they've created.