The information is not the inventory, because this particular information is not available for sale in a rivalrous fashion. Your attention is the inventory. (This is sometimes phrased sardonically as "If you're not paying for it, you are the product.")
Exactly. I've made the same comments re being the customer vs. the product regarding Facebook. Except with Facebook, there's a lot more than users' attention on offer to advertisers.
The real question is, would content quality improve if we paid for it directly, instead of indirectly through ads?
Another related question: What content would not exist if you had to charge for it and couldn't use ads?