Think about it this way: a view on YouTube is worth approximately $0.001 to the video creator. That means 1000 people have to watch your video to give you a measly $1. This is extraordinarily inefficient. $1 is about 6 minutes of labor on minimum wage in a developed country. 1000 people watching your video for a mere 6 minutes labor value or less than a can of coke.

Steem doesn't have to be very efficient to be better than ads. But it just so happens that it's actually a very efficient way to pass value from consumers to creators. The end result is that it beats ads and YouTube by several orders of magnitude.