An upgrade to Apple’s mobile operating system released Wednesday brought with it apps that can block ads inside the company’s default Web browser, Safari. It also brought a storm of debate about the ethics of ad blocking and the future of online publishing.

Two common claims are that ad blockers may strangle small publishers, and that they provide a way for consumers to force the ad industry to make more respectful ads. Both arguments rest on the assumption that ad blocking will make a significant dent in ad revenues–but there are good reasons to think that it won’t.

For one thing, ad blockers may not prove to be very popular after this week’s initial flurry of interest. More than a dozen ad blockers are now available in Apple’s App Store, and several feature on its list of the most popular paid apps. The developer behind Crystal, the app currently at number one, tells me that it was downloaded more than 100,000 times during its first 12 hours in the store, during which it was free (it now costs 99 cents).

However, there are 80 million active iPhones in the U.S. alone, according to Comscore. And Apple’s upgraded mobile operating system, iOS 9, is used by less than a quarter of iPhones thus far, according to mobile analytics company Mixpanel. It’s likely that the people who rushed to install the new iOS are more tech-savvy and interested in ad blockers than iPhone users as a whole. The new apps may soon disappear from the charts as more people upgrade their iPhones.

A second reason to doubt the impact of the new ad blockers is that they only block ads in the Safari browser. That means only a small slice of the ads people are subjected to on smartphones will be blocked. Ads inside mobile apps are unaffected by the new blockers, and so are those on webpages that open inside the “webview” that appears when you tap a link in, say, the Facebook or Twitter apps.

The time that people do spend looking at mobile webpages in Safari is a fraction of the time they spend in apps. In the US, 53 percent of time with digital media is spent in mobile apps, versus 8 percent on the mobile Web, according to a July report from Comscore. Accordingly, much less money is spent on ads on mobile webpages than on ads that are within mobile apps. Apps get 62 percent of the money spent on mobile ads, with the Web getting the other 38 percent, says mobile ad company Smaato.

One thing we do know for sure is that mobile ad blockers can make it faster to browse the Web, and save on the energy and bandwidth your device uses. The new choice Apple has made available by allowing these apps will help some people. Whether it will also significantly harm the ad industry and publishers is less certain.