Exactly. Everyone looks for the direct link for conflicts, but the networks' ability to sell advertising space to gambling companies I would think is a very significant slice of the pie they need to recoup in the cost outlay of securing the broadcasting rights.
The AFL does their part by creating a schedule to maximize viewership and gambling does their part by using TV to create new points of interest in a game beyond the actual contest on the field.
I have mates who turn on (and off games) subject to whether their multi is alive or not. They have no interest in the game's outcome other than margin spread.
that's sad.