I did not read this as suggesting advertising is useless, the author says outright that it can help build up a critical mass of brand recognition. But the auth

I did not read this as suggesting advertising is useless, the author says outright that it can help build up a critical mass of brand recognition. But the author's point is that once you reach that critical mass, advertising may begin to cannibalize your organic search results because users click on your ad instead of clicking on your site in the search results. I own a copy of "Ogilvy on Advertising" I bought in the 1980s. In it, David Ogilvy basically says, "test, test, test." That's the message here. Test. The advertising you're doing could be useless. I'm not sure I agree that when you reach a certain point, ALL advertising is useless. Maybe when you reach the point where most of your advertising has no ROI and is cannibalizing your organic SEO, you need to change your spend and try to find ways to get your ads onto search results that don't feature your site. If you find that works, you can then adjust your SEO and see if you can make that advertising go to zero ROI too. Lather, rinse, repeat.