Origin-served ads cannot be blocked by
host-based adblockers, but
can be blocked by hueristics-based adblockers.
I'd implemented a variant of this as banner ads began increasing in prevalence in the late 1990s / early aughts, using CSS to filter out standard banner sizes and path elements. Tools such as uBlock Origin incorporate far more sophisticated variants of this. It's also possible to block (or selectively permit) specific page elements with a CSS editor (e.g., Stylus), with web proxies (including SSL/TLS terminating proxies), or other means.
My experience is that if a site tries excessively hard to cram ads down my throat, I'll kill it and look elsewhere.
For a long time the argument was that this was a limited technically-sophisticated niche response, and that "the average person" didn't care and wouldn't bother. The increasing prevalence of ad-blocking tools and default incorporation (e.g., in the iOS platform) suggests that the barrier is knowledge and skill rather than of caring, and that people who can block ads in general will.
This itself should be a cautionary note to both advertisers and advertising platforms, as the trend will be to drive the audience bar further down sophistication and means capabilties, meaning what ad content is shown aims at less remunerative segments, and tends toward ever-increasingly noxious methods. That story ends poorly, as do most Gresham's Law dynamics.
(A similar point is made more pithily here: https://news.ycombinator.com/item?id=33067889>)