But that only would have lasted until the next search innovation and/or competitors copied Google's indexing.

There were many search engines around during that time. Yahoo, Excite, Microsoft Live Search, Lycos... I don't recall any of them improving enough to rival early 2000's Google.

None of those scaled as quickly as Google in terms of revenue (read: AdSense), and Microsoft lost interest.

AdSense wasn't a thing until 2003. Google didn't have much revenue before that. However, they still surpassed their competition in quality of search results long before...

Yes. My point is that Google had a temporary search quality advantage… then AdSense-fueled revenue allowed them to convert that to a durable moat by outspending their competitors.

That didn't happen because they were magically amazing at search forever.

It happened because Google had a good business plan and could afford to throw gobs of money at engineers and infrastructure, in quantities that even Microsoft was unwilling to match.

Was on a team that was trying to sell AltaVista a social media presence (before facebook/myspace/etc). Our people were mostly using Google, but we still wanted the client. One of the "moderation experts" on our side (i.e. - not tech or busniess) who evidently didn't understand what AltaVista was about asked them "Why don't you just use Google? It's better".