I grew up poor, my family didn't have disposable income for buying media. Everything I got, came from ad supported radio, TV, or public libraries. I used to call into radio stations to ask them to play a song, and then wait for hours so I could tape the songs and create tapes. Our family did not have cable, and though we had VHS, we often didn't rent movies, but rather used the VHS like a Tivo.
There are billions of people in the world who now have access to billions of Web documents that were paid for by advertisers, many of whom probably didn't even get their moneys worth. If the Web originated as a paywall, it would have never grown to the size and usage rates that exists today.
The first crawlers would have never arisen if anyone wanting to built a search index had to strike deals to access content for indexing.
Paywalls raise transaction barriers that ads do not. Ads make you pay in bandwidth and time, but for much of the internet's life, those were tradeoffs that were much easier to make than having to break out a credit card everytime you saw an article that MIGHT interest you. Paywalls also make centralizing vs federated/decentralized content more economically efficient.
How many of you have searched for scientific papers only to be pissed that they're behind some Springer-Verlag paywall?
Do we want to live in a world of walls, or a world of open highways with billboards? That's the choice being made here. And the scorn being heaped on ads is the luxury and privilege of living in a time when most of the content on the Web and most of the infrastructure costs have already been sunk and payed for by advertisers in years past. We live in a Web of excess now, forgetting the hundreds of billions sunk into datacenters and network infrastructure and content creation that came before. Who paid for that, and would it have even existed if the entire thing was like Cable TV premium channels?
I don't really want the Web to turn into a giant Apple Store, where every link, I must face the cognitive burden of paying for it before I know that I even want it. We need to solve the issues that ads create with respect to bandwidth hogging and privacy, but I think paywalls, even micro-payment paywalls, impose too much of a transaction cost and cognitive burden for the free exchange of knowledge.