This 'users are the product, advertisers are the customer' insight can be useful, but can also be overdone.
It's also useful to recognize that for some of Google's lines of business, the payment offered is not money, but attention (or perhaps habit). Then, searchers are again customers, after a fashion.
This better recognizes the searchers' customer-like power, in some dimensions. Otherwise, as just the 'product', were they mined from the ground? Grown like crops? Manufactured? No, their attention was acquired in a voluntary, market-like but non-monetary exchange of value for value.