Monopolies aren't necesarily bad in-and-of-themselves. The trouble starts when a monopoly in one market is used to gain an advantage in another.
So, having a monopoly in the search engine market isn't necessarily a problem (especially given the low switching costs you noted), but leveraging that monopoly to compete with non-search-engine companies by essentially choking off their search engine traffic is a BIG problem.
The exact means used that results in said choking-off may or may not matter (this is where the incoherence pops up), but the fact is that the conduct of any company with a monopoly (including entirely legitimate and legal ones) MUST face additional scrutiny for how it affects other markets.
When it was just starting out, Google was proud of how quickly users left Google search results by clicking a link. AFAICT, that didn't change until sometime well after AdWords was introduced (in fact, how quickly users left was an AdWords selling point and increased competition for the top ad slots), but at some point, Google started cannibalizing their SERP traffic in various ways. It was going to bite them in the ass sooner or later.
So, having a monopoly in the search engine market isn't necessarily a problem (especially given the low switching costs you noted), but leveraging that monopoly to compete with non-search-engine companies by essentially choking off their search engine traffic is a BIG problem.
The exact means used that results in said choking-off may or may not matter (this is where the incoherence pops up), but the fact is that the conduct of any company with a monopoly (including entirely legitimate and legal ones) MUST face additional scrutiny for how it affects other markets.
When it was just starting out, Google was proud of how quickly users left Google search results by clicking a link. AFAICT, that didn't change until sometime well after AdWords was introduced (in fact, how quickly users left was an AdWords selling point and increased competition for the top ad slots), but at some point, Google started cannibalizing their SERP traffic in various ways. It was going to bite them in the ass sooner or later.