Sites can take advantage of the functionality of an ad-blocker to detect its presence, e.g. by creating a document element that will look like an ad (and so be blocked) and then testing for the presence or absence of that element. If the element is not found they could assume that their ad is not seen in the browser.
As I don't run any web sites I don't know whether ad views actually factor into their payments to site owners. But it seems clear that ad blockers can be detected. That may result in a cat-and-mouse game between blockers and advertisers of mitigations against detection, detection of those mitigations, etc.
Also, ABP has features like allowing "acceptable advertisements" and advertiser whitelists.