Are you suggesting that I have some obligation to download the object at the other end of a URL just because it happened to be embedded in a tag on a page I chose to view?

A URL is just an advertisement for a resource which is available on the web. Since when does seeing an advertisement obligate you to go acquire the object being advertised? Must I compensate the makers of highway billboards for the work they did presenting those advertisements, if I happen not to want to purchase their products?

No, it doesn't work like that. Web publishers can hope all they want that I choose to accept their invitations to download ads and look at them, but it's my machine and I'm paying for my own bandwidth, so I'll make my own choices about what to do with it. An adblocker is nothing more than an intelligent assistant for making those choices.