Some people just don't want ads. Paradoxically, the sites I care most about are the ones I want to periodically visit, and enjoy without the ads. So the ad blocker will have filters fine tuned for those.
Is that a sustainable business model? Well, no. There's a direct donation on sites nowadays luckily.
I'm not saying you can't make ads completely indistinguishable from content but I also don't think that's the solution that we want either.