You could invent the wheel and there will be no demand to harvest because everyone has always dragged their dinner back to the cave. A caveman will never do a Google search for a wheel.
Trying to educate a market that they need your product is a losing proposition. Trust me.
Let's say you release "Brand New Purple Foobars!" and hire my ad firm to advertise them. Sales are up, so what's your conclusion? Well, maybe my ads really helped push your product. OR maybe your product was just so awesome on its own that it didn't need any advertising. The question is, if you don't know for certain which it was, do you take the risk of not hiring my ad firm next time? What if you don't, but your competitor that just came out with "Brand New Yellow Doohickeys!" does?
The problem with Google's ads is that it removes the mystery. If I know how many people saw the ad, and how many people followed through and clicked the link, then I can evaluate how effective my ad campaign is directly. It's like giving the prisoners cell phones so they can text each other… "Hey, they said you confessed…that true?" "Nah man, you?" "Nope!" "Cool…so drinks later?"
Do you really think marketers want to blow all their money without returns? Why do you think Google Adwords is so popular in the first place?
And a final note, from someone who worked at a large agency that focused on media buying: display ads often reinforce a keyword/CPM/CPC campaign and lead to better overall results, despite how ridiculous that sounds.
Facebook ads might make more money than Google ads precisely because their effectiveness cannot be measured (just like TV and billboard ads). Sure, engineers will cite poor CTRs but "brand managers" will be eager to dismiss that as oh-so-2001. They are not buying clicks, they are creating "brand awareness on the largest website on the internet".