Apple is coming for ads. It's coming for publishers. And, in the process, it may be gunning for the web.

At its Worldwide Developers Conference this week, Apple demoed iOS 9, showing off a smarter Siri and a more useful wallet. But it didn't share everything. Later, buried in documentation released after the conference, the company revealed another update to iOS 9—app developers will be able to create ad blocking software for Safari's mobile browser.

Ad blocking is nothing new. Users have long downloaded extensions to block ads on their desktop browser of choice to better protect their privacy, improve load times, save battery life, and, well, block those pesky pop-ups and annoying banner ads. But, according to the Interactive Advertising Bureau, ad blocking has become so popular that it poses a danger to marketers, entertainers, and publishers.

Ads don't exist just to track and annoy consumers. For publishers and entertainment sites, ads pay the bills.

And mobile ads are next. Consumers are spending more of their digital time on their phones—and Apple wants to own that experience. While iPhone users can download third-party browsers, the majority of mobile and tablet users in the US use Apple's own Safari browser. So, even though some limited ad block options have existed for iOS and Android in the past, this is the first time Apple is giving mobile ad blocking its official blessing.

But why now?

As evidenced at WWDC, Apple is trying to pull iPhone and iPad users off the web. It wants you to read, watch, search, and listen in its Apple-certified walled gardens known as apps. It makes apps, it approves apps, and it profits from apps. But, for its plan to work, the company will need those entertainers and publishers to funnel their content to where Apple wants it to be. As the company makes strategic moves to devalue the web in favor of apps, those content creators dependent on ads to stay afloat may be forced to play along with Apple.

Ads Matter

Ads don't exist just to track and annoy consumers. For publishers and entertainment sites, ads pay the bills. Google, Facebook, and Twitter run on ads. YouTube, Hulu, and WIRED run on ads. Apple, however, does not. Although it has its proprietary advertising platform iAd, Apple's revenue comes overwhelmingly from its hardware, with iTunes and App Store contributing a much more modest fraction.

As such, Apple has a compelling reason to make the experience of using that hardware more appealing. A Safari without ads is a more desirable browser for users to use. Android users, for example, can already download ad block software or a special browser with the software built-in. If more users don't want to see ads, Apple is smart to provide that option for them to achieve parity with the rival mobile OS.

Ad blocking plays into Apple's competition with Google in another way, too. As Nieman Lab's Joshua Benton notes in his look at how Apple's latest move could hurt publishers, Google depends almost entirely on ads for revenue. By one estimate, the giant may be losing billions of dollars from these kind of browser blocking extensions. Google has tried to fight back by blocking AdBlock Plus—one of the most popular ad blocking browser extensions—in 2013, but, ultimately the company has reportedly opted for paying the service to save its search ads. By incorporating its own ad block capabilities in Safari, Apple could be kneecapping its archrival while innocently claiming its just trying to improve the user experience.

A Groomed Garden

If Apple does truly want to get users out of browsers and into its apps, it will need to have publishers and entertainers on board. And the best way to do that may be to force those content creators into a position where they stand to make the most money if they allow Apple to serve as the conduit to their audiences. While Apple may be fine with blocking ads in Safari, there's no indication it plans to block ads in its new News app. The company may be betting that if it can make bringing in revenue on mobile even more difficult for publishers, then everyone will be more willing to publish stories directly within News.

Apple is betting that consumers will go where the best stuff is, and where they find the easiest, most beautiful experience. But, there's no such thing as free.

At the same time, the mobile web may not be that big a loss for publishers anyway. Though readers have gravitated to mobile devices as their screens of choice, publishers haven't figured out how to make all that much money there. The New York Times, for example, makes just 10 percent of its total revenue on mobile, despite the fact most readers read stories on their phones. For publishers, ad blocking may just lead to a jump in sponsored or native content, or more publisher-produced paid apps, such as the upcoming What's News from The Wall Street Journal.

Then again, it doesn't seem like ad blocking will be the default—users will have to know about the option and choose to block ads. The change may not be as sweeping as readers in the know might expect.

And yet if more ad blocking does make publishers more dependent on third-party platforms such as Apple News, Facebook Instant Articles, and Snapchat Discover, it could help consolidate those companies' power as gatekeepers to determine what qualifies as news. While big publishers likely won't suffer under such a regime, the little guys that form the fabric of the web may slowly start to fade. Smaller publishers, bloggers, and niche sites won't have the clout to get the premium placement or partnership with third parties that future success may demand. Without ads, it's the little guys that could suffer the most.

So yeah, the web isn't dead, per se, but it's changing. And, if Apple has its way, apps will usurp its centrality. Apple is betting that consumers will go where the best stuff is, and where they find the easiest, most beautiful experience. But, there's no such thing as free. The web is fragmented, disjointed, and hard to control. It seems free to users. But it's ads that keeps content creators' lights on.