Mozilla on Friday abruptly announced that it was pulling the plug on what it called Firefox for Metro, the Modern version of its web browser for Windows 8.x and RT. The reason? Virtually no one is testing the software, indicating that Microsoft's new mobile environment is dead in the water.

"From what we can see, Metro's adoption is pretty flat," Mozilla Firefox VP Johnathan Nightingale writes in a blog post explaining the strategy change. "On any given day we have, for instance, millions of people testing pre-release versions of Firefox desktop, but we've never seen more than 1000 active daily users in the Metro environment."

Note: "Metro" was the original name for the mobile environment that Microsoft included first with Windows 8. But after getting sued over the name, Microsoft stopped using it, opting instead for such terms as "immersive," "Modern," and "Windows Store." This naming silliness is only a small part of the debacle that is this mobile environment.

Nightingale says that while Mozilla worked for two years to deliver a beta version of Firefox for Metro, "shipping a 1.0 version, given the broader context we see for the Metro platform, would be a mistake." It's just not popular enough.

"We could ship it, but it means doing so without much real-world testing," he writes. "That's going to mean lots of bugs discovered in the field, requiring a lot of follow up engineering, design, and QA effort. To ship it without doing that follow up work is not an option. If we release a product, we maintain it through end of life. When I talk about the need to pick our battles, this feels like a bad one to pick: significant investment and low impact."

"Instead, we pull it," he continues. "This opens up the risk that Metro might take off tomorrow and we'd have to scramble to catch back up, but that's a better risk for us to take than the real costs of investment in a platform our users have shown little sign of adopting."

While I'm sure some will try to undercut this problem by belittling Mozilla or Firefox in some way, that kind of argument is wrongheaded: These guys supported the platform and just didn't see the usage. And that is a very real problem. Part of the issue, of course, is Microsoft's wrong-headed decision to limit how browser makers can build high-quality products for the Modern environment (i.e. it's impossible), something that makes Windows RT in particular less desirable.

Not good.