The makers of the two biggest web browser competitors to Internet Explorer (IE) are complaining that the version of Windows 8 aimed at ARM-based tablets, called Windows RT, won't support any desktop browser other than Microsoft’s.

Mozilla kicked off the fireworks Wednesday with a post to its corporate blog, noting that although the ARM-based Windows RT will provide a desktop environment that is largely identical to that of mainstream Windows 8 versions, Microsoft isn't allowing developers to create desktop versions of their applications for Windows RT.

“Given that IE can run in [the desktop] on ARM [-based versions of Windows 8], there is no technical reason to conclude other browsers can’t do the same,” Mozilla General Counsel Harvey Anderson writes on the Mozilla Blog. “[But] Windows on ARM—as currently designed—restricts user choice, reduces competition, and chills innovation. By allowing only IE to perform the advanced functions of a modern web browser, third-party browsers are effectively excluded from the platform.”

Actually, it’s worse than that.

Mozilla’s Asa Dotzler says that Microsoft’s restrictions on ARM go well beyond the original complaint. “On ARM chips, Microsoft gives IE access to special APIs absolutely necessary for building a modern browser that it won't give to other browsers,” he claims in a post to his own blog. “So there's no way another browser can possibly compete with IE in terms of features or performance.”

“IE on ARM has access to win32 APIs even when it's running in Metro mode,” he adds in a follow-up post. “But no other Metro browser has that same access. Without that access, no other browser has a prayer of being competitive with IE.”

Mozilla isn’t alone in voicing its concern about this apparent design decision.

“We share the concerns Mozilla has raised regarding the Windows 8 environment restricting user choice and innovation,” a Google statement reads. “We've always welcomed innovation in the browser space across all platforms and strongly believe that having great competitors makes us all work harder. In the end, consumers and developers benefit the most from robust competition.”

If only it were that simple.

Truth is, no one outside of Steven Sinofsky’s inner circle at Microsoft really knows exactly what limitations and opportunities Windows RT will present to developers. And the reason is simple: Information oozes out of Microsoft at a snail’s pace these days, and customers are told only what Microsoft believes they need to know, and when.

Too, no developers outside of Microsoft even have Windows RT devices yet with which to test. So Windows RT is very much an open question, despite a few voluminous Microsoft blog posts on the topic. Will Microsoft provide native, Win32-style API and developer tool support for those plucky programmers who wish to port their desktop applications and utilities to Windows RT? It doesn’t appear so.

 “Windows on ARM does not support running, emulating, or porting existing x86/64 desktop app[lications],” Microsoft noted in a typically long-winded and dense post to the Building Windows 8 Blog. “Consumers obtain all software, including device drivers, through the Windows Store and Microsoft Update or Windows Update.” That last bit is interesting because it suggests that users of Windows RT wouldn’t be able to download any executable programs—including desktop applications and utilities—from the web. With Windows RT, the locked-down Windows Store is your only avenue for acquiring new Metro-style apps and other executables.

However, Microsoft has set no such limitations on itself. Windows RT—or Windows on ARM as it was previously known—not only ships with a full complement of Windows 8 desktop utilities (only two features, Windows Media Player and Storage Spaces, aren't present) but also includes full desktop versions of IE and—get this—four Microsoft Office 15 desktop applications: Word, Excel, PowerPoint, and OneNote.

Before the antitrust villagers grab their pitchforks and torches, however, let’s review for a moment how this compares with Apple’s and Google’s mobile platforms. For its iOS system, Apple provides similar limitations to Microsoft: In fact, one might argue that Microsoft simply copied (or “reimagined”) the Apple playbook when it created its own app infrastructure for Windows RT and Windows 8. With Google, this kind of restraint is in place on Android by default, but users can easily flip a settings switch that lets them acquire software for their device from any source, trusted or not.

Of course, neither iOS nor Android is bridging the same gap between new and old that Microsoft is with Windows 8 and Windows RT. What Mozilla and Google are really complaining about is two-fold. First, Microsoft is preventing them from doing with Windows RT what they did with previous Windows versions, and this will most assuredly be confusing to customers too. And second, Mozilla in particular is alleging that Microsoft is restricting third-party developers in ways that it isn't with its own in-house developers, giving Microsoft’s own solutions a priority and advantage over the competition. Assuming this claim is true, it’s a fairly damning accusation.

Even assuming Microsoft is indeed limiting third-party developers on Windows RT, it’s not clear this warrants antitrust attention. Sure, Microsoft still commands about 90 percent of the market for PCs. But Windows RT-based systems are not PCs, no more than iPads are; they’re devices, just like the iPad or smartphones. And calling Microsoft even an underdog in the tablet market is a bit of a stretch. It’s more of an also-ran, with even the most positive of predictions giving Windows RT just a tiny percentage of the market years down the road.

My guess is that Microsoft’s presumed actions here, while morally and creatively bankrupt, aren't illegal. And let’s face it: The company is being no less restrictive with Windows RT than is Apple with iOS. In this case, a sub-underdog is simply taking its cues from a market leader. So charge Microsoft with copying Apple yet again, please. But call off the antitrust hounds. There’s nothing to see here ... from that perspective.

That said, I do hope that these complaints raise enough of a stink that Microsoft backs off from what appears to be a very limiting aspect of Windows RT. We get it, Microsoft. Metro-style apps are the future. But it’s 2012, so let developers move to Metro in their own time and give them a chance to see what ARM is all about by porting their existing applications first. It’s the right thing to do.