[gruez]

>If all of the cleaning businesses in the area slash their marketing budget to 0, the author is not going to fail to find a cleaner.

You're right, they'll find whatever incumbent cleaner instead. A marketing ban is something that all incumbents would love, because they don't need to attract more customers whereas marketing is basically the only way that upstarts can get a foothold.

[owisd]

When Google has the monopoly on marketing of cleaning companies in your area, from a consumer standpoint it’s effectively the same as if one cleaning company has the local monopoly. The way to win is to pay Google a bigger cut than your competitors, so Google just takes the incumbency premium as its marketing fee instead of the cleaning company.