True, but my point was that even a lot of the commercial websites that do have other products do not depend on ads, e.g. Amazon and all the other stores would still be there, every company offering a paid service would still be there, every company providing a service related to their RL goods (e.g. specs, drivers, product descriptions, lists of stores where you can buy them,...) would still be there.

Advertising does not finance a very large percentage of the useful parts of the internet. And among those advertising financed websites that are useful a lot are essentially duplicates to get a chunk of the ad revenue without doing a lot of work (e.g. almost all news websites that just republish AP, Reuters,... content).