Increasing cost was the thought, yes. I admit I'm not totally up-to-speed on what adblock and ublock do, but I was under the impression that they don't load the ads. So while you wouldn't see them, there's also no cost to serving them.

Edit: But are the advertisers really paying for those clicks? Reading through the thread, it seems like these get flagged as fraud pretty easily. So while there's still a cost to create/serve the ads, to the point of my question, it would seem they don't pay the websites for the clicks.