People also forget how inexpensive and ephemeral individual ads are. A display banner on a quality site costs less than a tenth of a penny.

And it’s like a room on a cruise ship — the boat is gonna sail one way or another. So it has to be sold.

Advertisers might choose to let Facebook arbitrage those impressions into a cost per click model — at pennies per click instead of hundredths per view. Tradeoffs galore in that model.

When you aggregate these numbers into a $600b industry, you start to see how sweating some of the finer details just doesn’t matter.