define "moat", Open source search engines and competitive scraping strategies were built in the early 2000s. The Google search moat has always been that they were better for 5-6 years - and then they were the default.
Once they were the default option, they merely had to be the "same" as other options. If someone were to make a 1:1 clone of google with ~5% fewer ads - I do not believe they would break get a substantial market share of web search traffic (see bing).
