I'm not sure that was the predominant reason. The search results were also a hell of a lot better than AltaVista, Lycos, Yahoo and whatever else was around back then.
Google was a huge improvement because if you searched for Foo Bar Baz it would only give you pages that had all the words Foo, Bar and Baz whereas AltaVista et al. would give you pages containing any of the words, if memory serves. But the speed was a huge deal too, especially on a 56k modem (and the thing had to be rendered in IE4 on a Pentium II too, let's not forget).
AltaVista had a full set of boolean operators, so you could search for [Foo AND (Bar OR Baz) AND NOT Quux], which I still miss. Google appeared just when AltaVista ‘graduated’ from a showpiece for the Alpha to trying to make money and therefore turned to crap.
Yes. In particular, Google's search were much better for ordinary users who didn't do complex searches....