> Google Search doesn’t have a network effect right?

In this specific case it does :-

1. People go to google because it is more likely to have the result they are looking for[1],

2. So, people can't search elsewhere, because the network of sites are on google and they lose that if they switch.

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[1] Well, until recently, anyway. Still, sites prioritise and optimise for Google search ranking above all other indexes.