[summerlight]

This is one of significant misconception for digital marketing. More ads doesn't necessarily mean more revenue since it's bound by total advertising budget. Let's assume an optimal ads market and you put more ads there without further optimization or budget, then there will be less auction pressure per ads (thus less CPM) and roughly similar revenue. For something like 40% YoY growth at Google's scale, you need to convince big advertisers to allocate more budgets.