On Monday an extraordinary letter went out from a who’s who of major corporations claiming a mandate to track all of us on the internet. In tone and substance, it is an amazing, over-the-top screed against efforts to give consumers even modest controls over who watches us as we surf online.

The letter was triggered by Microsoft’s announcement in May that when it ships its new browser, IE 10, the browser’s default setting will be Do Not Track. Microsoft heard the vast preference of its users and is giving them the default setting they want—no tracking of their movements and habits online. Consumers who want to get targeted ads will still be able to do so—and in fact will get a chance to turn that preference on when the program loads. As we said at the time, this is exactly the right decision, a powerful tool for giving back American’s their privacy online.

The Association of Network Advertisers (ANA), which organized the letter, is a major industry group; the letter is signed by 36 major corporations including General Mills, American Express, General Motors, Verizon, Visa, Walmart, Bank of America, and many others. To say they are unhappy with Microsoft’s decision seems to be a major understatement:

[T]his action was shocking … Since the initial letter, Microsoft’s announcement has been uniformly met with outrage, opposition, and declarations that Microsoft’s action is wrong. The entire media ecosystem has condemned this action.

Why?

Microsoft’s Internet Explorer Browser currently has a 43 percent market share in the United States. By setting the Internet Explorer browser to block data collection, Microsoft’s action could potentially eliminate the ability to collect web viewing data of up to 43 percent of the browsers used by Americans.

Keep in mind that many companies have supported Do Not Track in the past, when the default was allowing consumers to be tracked. The letter actually says, “it is clear that a default ‘off’ setting for consumers to control online data collection strikes the right balance for society as a whole.” Even if it’s directly against the clear preference of the citizens who make up that society? It’s hard to reach any conclusion but that companies were fine with giving consumers a choice as long as they assumed it wouldn’t be exercised.

The letter also trots out the canard that the free internet is at stake and portrays this as a decision that prevents the ad-supported internet. Of course this is completely untrue. Ads will always be part of a free service—they just won’t be ads that build an elaborate model for constant, real time tracking. In fact there is a long history of immensely popular, free content supported by ads—it’s called network television.

Perhaps the most revealing part of the ANA letter comes right at the beginning. It’s addressed “Dear Steve, Brad, and Craig.” They are respectively Microsoft’s CEO, General Counsel and Chief Research and Strategy Officer, Steve Ballmer, Brad Smith, and Craig Mundie. It’s the address you’d use with a friend. In some ways the letter reads like a message to dear friends who have disappointed you with their errors and wrongheaded action. Perhaps this sense of betrayal means that Microsoft is onto something. By supporting Do Not Track, they are putting up a real barrier to pervasive online surveillance. That seems like a strong reason to send a clear message to companies to protect our privacy online.