This is effectively a straw-man.
Treating advertising a way to connect suppliers with those with a need is a common, benign interpretation of what it is, but that view rests on assumptions of trust or informational parity between buyers and sellers. i.e. the sellers have to be meeting genuine needs, or the buyers have to have the information necessary to make good determinations. I don't see why we should assume that's generally true. There are plenty of counterexamples (e.g. Drug companies advertising drugs for conditions for which there is not good evidence of efficacy, and consumers being unable to evaluate the statements for themselves).
Google makes its revenue by auctioning qualified snippets of human attention. By qualified, I mean that it makes algorithmic inferences about the users demographics and intentions and uses these to bucket these snippets of attention so that they can be priced differentially. This is why Google's advertising is so much more profitable than most other forms.
At best, I think you can say that Google's advertising is neutral. The value it provides to society is determined by the qualities of the buyers and sellers.
A more skeptical view would be to point out that buyers are better informed than sellers when they enter these transactions. For example, google's search users don't get to see the price that google is charging for their attention, nor are the mechanisms by which google intends to use, say the Google+ network to improve classification transparent to us.
You can reasonably claim that it would be preposterous (or uncompetitive) for Google to reveal these mechanisms, or that Google couldn't survive such a climate of openness. Certainly their competitors are probably worse. That doesn't mean we should be any less critical.
I think that the more informed we are about how we use our attention, the better, and it's not clear that Google, or any other advertising company is automatically aligned with society in this regard.