A series of studies by Robert Epstein show how manipulation of search results can change voting substantially.
We in SEO may end up all working for various political campaigns.
In any case, this proves the effectiveness of SEO.
It’s actually stronger than that for a further reason. In any market space, there may be a few thousand competitors. But there are only a handful of serious competitors (companies that make an effort to provide better service/products than their competitors, etc.) And of that, only a few are excellent at all forms of marketing (offline, TV, digital, etc.) These few get the bulk of the market (both customers and revenues). So a well-structured digital campaign (unified SEO, PPC, content, social, etc.) can significantly improve an organization’s visibility within its field.