There was a time when it was incredible that a small team like Google could somehow implement search more effectively than a company that has years of search experience (i.e. AltaVista)
In that case -- and probably in the case of Kagi vs. Google as well -- it was entirely dependent on focus. In the hypothetical situation where your goal changes from "provide the best possible search" to "beat Yahoo," your available resources will be used on different things, and then...