For as long as there have been ads, there have been ways to avoid seeing them.
Technology has kept pace on both sides, but ad-blocking has never really become mainstream. It remained the domain of the tinkerers, who knew about browser extensions at the very least, or proxies, or hosts files. Extensions were as approachable as blocking has ever been, but the vast majority of normal (i.e. non-technical) people probably don’t go anywhere near them. And so the ads were always seen.
Things are starting to change. Legislation, public perception, and consumer-focused functionality have all woken up to issues of privacy, intrusive tracking, and our never-ending exposure to advertising.
We’re slowly realising that we have options, and that we should perhaps begin to exercise them.