While consumers have been finding ways to block ads as long as there has been advertising, the rapid rise of browser-based ad blockers may represent an even more existential threat than people simply turning the channel or their heads to bypass an ad message. That’s because with ad blockers, the ads never even get served, so there’s no opportunity for the ad to be seen or ignored.

While the use of ad blockers has been reaching a critical mass for years, no supplier has become more associated with the phenomenon on Madison Avenue than Adblock Plus. That’s partly because it’s penetrated the most deeply into the marketplace to become  the best known ad-blocking application — but also  because it has been leveraging that position to create a new gatekeeping paradigm in the ad marketplace.

Despite the antithetical notion that an ad blocker could be an ally of advertising, the company’s executives stepped up their visibility, speaking at industry events and meeting with advertisers, agencies and publishers in an effort to develop new models that would simultaneously give consumers control over their browser experience, but also enable the right kind of ads to get through.

The company has tried to position itself as a solution rather than a threat, enabling consumers to “whitelist” brands and ads that Adblock Plus gets paid for passing through.

To many on Madison Avenue, though, the practice is tantamount to a shakedown racket in which publishers pay for the right to serve ads to their own users.

To date, the response from Madison Avenue and most major publishers could be described as tepid at best, but the company continues plugging away, developing its own captive advertising network and pitching big brands and agencies to be part of its Acceptable Ads Committee.

It remains to be seen whether Adblock Plus will emerge as a new intermediary between consumers and brands. Still, it already has had an important positive effect on the advertising industry, according to Wharton marketing professor Jerry Wind.

Speaking at the Media Future Summit last fall, Wind said Adblock Plus is forcing the ad industry to rethink its core proposition, especially the kind of ads it creates for consumers — and the reasons consumers will or will not block them.

Whether Adblock Plus proves to be an enemy or a frenemy of the ad industry in the long run, one thing is clear in the short run: It got industry members to think about the fundamental nature of engaging consumers in a world where their ads could be automatically blocked.