Also, let's not forget what's really going on as a part of this "transaction," which is that a website is sending data to my computer, which I own. That data includes requests for my computer to perform certain operations, show me some ads, maybe hand over my online banking passwords, etc. etc.

I am absolutely within my rights if I instruct my computer to honor some of these requests and not others. Any other perspective is crazy when you think about it. I own the computer, I choose the programs that I run. I'm not leasing this computer from Google or from the business that owns the website in question.

This is really a matter of property rights. If somebody wants me to use a computer which is unable to block ads, they can offer to lend me a free computer which has that limitation, I suppose. I mean I'd say no, but other people might say yes.