I could have been more clear: I don't understand why the non-advertising business's interest is aligned with that of the user. I follow the idea that advertising creates a conflict of interests, but I don't follow that not advertising aligns interests. The business is there to sell a product for the most profit. Making money by selling the product doesn't by itself give them an incentive to produce a better product.
If they don't make the website provide value to me, I will stop paying them. If things are popping up that are irrelevant to my search, that's not helping me. If it's not helping me, I stop paying, and they feel a hit. It's probably not a big deal if a single person does it, but if enough people do it, then they either change to get those people back (or replace them with new customers), or they go out of business.
I don't entirely follow, though; the idea is that you want the people who pay you to be satisfied with what they're paying for so that they continue to do so, convince others to do so, and are willing to increase their spending. If that wasn't the case, there wouldn't be a conflict of interest for advertisers in the first place.
There's reasons that the incentive to keep the users satisfied may not be followed, but it's mostly tangential, and relates more to other forces than it does where the money comes from.
