I may not have been very clear about the point I was trying to make. Search (and other services) do make up their core business, and people confuse the issue when they exclusively focus on advertising because it is the source of most of their revenues.
One could choose to talk about Mozilla as a front end to Google, or newspapers and broadcast television channels as sellers of advertising. However, focusing on this intermediate step to the exclusion of the complete system obscures rather than clarifies an understanding of how these businesses operate.
It is not merely a question of semantics. Fixating on advertising alone doesn't shed much light on how Google optimizes its business decisions and creates value for its owners. A parallel might be to focus only on the income statement, cash flow statement, or balance sheet of a company rather than looking at all three. Narrow perspectives, even when masquerading as pithiness or cynicism, are poor aids to understanding.
