I know all this. But again: In practice ad blockers work reasonably well. Yes, some ads manage to pass through, but most get blocked. It effectively improves the user's experience.
The absolute stance would be to say that either you have to accept the websites render ton of ads, because there is no guaranteed way of blocking them, or you stop using the web. But some people prefer the non-absolutist way, that is to use an ad blocker.