Where they once controlled the entire process from creation to consumption, media companies now see their power over almost all the elements of that value chain ebbing rapidly.

As Facebook tries to get publishers to host all of their content on its platform with features like Instant Articles, which provides faster-loading mobile pages for those who give Facebook control over their pages, Google has been trying to present an alternative that it says is more open and more flexible—a feature known as AMP, short for Accelerated Mobile Pages.

In its pitch for AMP, which officially launched in February, Google has stressed that it is trying to help strengthen the open web because it wants to blunt the force of walled gardens like Facebook (FB).

Unlike Instant Articles, the AMP standard is an open-source project, one to which any publisher can contribute. As Google’s head of news, Richard Gingras, put it earlier this year:

There’s a very big difference between having a proprietary platform that says it’s open, and having an open-source platform that is open to anyone to modify and adapt. It’s the difference between saying come into my walled garden vs. not having a walled garden.

Not everyone is convinced that Google (GOOG) really has their best interests at heart, however. Some media companies believe that what the search giant really wants is to strengthen its control over the web—and more specifically, its control over how the web is monetized.

In a nutshell, these publishers are afraid that while the AMP project is nominally open-source, Google is using it to shape how the mobile web works, and in particular, to ensure a steady stream of advertising revenue—something that Facebook’s Instant Articles threatens to erode. (Google also recently said it is trying to apply AMP principles to ads as well.)

Without going into too much detail (there’s more on the technical aspects of the standard here), AMP is a variation on HTML, the code that underlies the web with additional features that speed up page loading.

Google maintains that one of the things AMP is designed to do is make the user experience better because publishers have added so many pop-up and auto-playing ads amid other annoying ad formats that slow down pages and also irritate users into installing ad-blocking software.

But some publishers say this is a smokescreen designed to obscure what Google really wants.

“The argument that they are doing this because we create crappy experiences is BS,” said one publisher who didn’t want to be identified. “They are doing it because they want all the advertising revenue.” Although there are non-Google monetization methods built into AMP, this publisher insisted, “they amount to peanuts.”

Others have raised similar complaints. They say AMP is not actually supporting the open web because it is a “fork” or variation on HTML and one that Google essentially controls. Although it is an open-source project, Google ultimately determines what is added to the standard and when, these critics say.

In an interview, Gingras admitted that some of the existing methods publishers use to generate revenue on their pages are not supported in the AMP standard, such as pop-ups.

“Some of the issues are ad behaviors that are extremely annoying and have caused people to install ad blockers,” the Google executive told Fortune. “So AMP has decided that certain behaviors aren’t supported. Obviously, there are revenue implications associated with that for publishers.”

Gingras said these decisions aren’t being made by Google, but rather by an AMP working group consisting of publishers, advertising technology companies like Rubicon and OpenX, and other providers such as Outbrain and Taboola. The group is open to anyone, and all the information about its decisions is made public, Gingras noted, as it is with any open-source project.

Google’s head of news said that the company has been very careful not to exert too much influence over the AMP project, and to get as many outside companies as possible involved.

“I can’t stress enough that it’s a collaborative effort with lots and lots of publishers—anyone can join and help develop it,” Gingras said. “This is an open-source project and we are managing it very, very carefully as an open-source project. I’ve said from the beginning, if it is a leadership of one, i.e. Google, it won’t work. We need everyone in the ecosystem to be involved.”

Some publishers have complained that as Google prioritizes AMP links—as it recently said it will do in mobile search—media companies will lose even more control because AMP pages are hosted and controlled by Google. “Our mobile search traffic is moving to be majority AMP (google hosted and not on our site) which limits our control over UI, monetization et al,” said one digital media executive.

bingo. Worse yet, AMP pages from SERP don't even direct users to pubs' domain. Google replaces your domain with theirs

— name (@eric_young_1) August 4, 2016

Gingras, however, replied that this fear is unfounded. Although Google loads AMP pages from its own servers using a cached or stored version, this is done only to speed up loading times, he said. Although some ad formats are not allowed, the underlying page is controlled by the publisher, and the cached version is updated whenever there is a change in the page.

Not only that, Gingras continued, but the AMP project gives publishers a lot more control over monetization than Facebook does with Instant Articles.

“Yes, it is served out of the cache for performance reasons, but the traffic coming out of search goes to the publisher’s page,” said Gingras. “Everything about it is the publisher’s—the links are theirs, the ads are theirs, the analytics are theirs, and so on.”

More than anything else, the concerns that some publishers have about AMP seems to be part of a broader fear about the loss of control over distribution in a platform-centric world, and the risks that this poses to traditional monetization methods such as display advertising.

In that battle, Gingras maintained Google is on the side of publishers and the open web—and not just pushing AMP for its own purposes.

“Our objective is to get the web to a position where it’s compelling, and not as vulnerable to platforms that want to move away from the web itself,” Gingras said. “It’s not Google vs. Facebook. It’s Google trying to maintain the health of the open web so that it can compete with Facebook. If you study the history of proprietary platforms, it typically doesn’t play out well for the content provider.”