If you use a Windows 10 mobile device for reading ebooks, you might have to resign yourself to switching platforms eventually.

According to CNet, corporate vice president of Windows 10 and head of Microsoft’s “PC-Tablet-Phone” division Joe Belfiore has tweeted that Microsoft is pulling back from new Windows 10 mobile software and devices. The company will continue to provide security fixes, and support companies that are heavily invested in the platform and roll it out to their users, but it’s apparently no longer going to throw good money after bad when it comes to trying to build out the ecosystem.

The reason? Microsoft simply hasn’t been able to cajole or incentivize enough developers to make apps for the platform. Even Bill Gates gave up on Windows phone and switched to Android, and Belfiore himself has admitted to doing the same, citing the bigger ecosystem as the reason.

None of the articles I’ve been able to find about this matter is entirely clear on what these tweets from Belfiore mean, perhaps because Belfiore himself isn’t clear in them. (This Ars Technica piece chronicling the history of Windows 10 on mobile devices seems to be the best of the bunch.) The most direct they get is saying that new features and hardware for mobile Windows 10 is “not the focus” anymore (because that’s what Belfiore said). But when the head of the division and even the corporation’s founder are no longer willing to eat their own dog food, it seems pretty clear they’ve given up.

It’s not much of a surprise, either. Windows mobile has been ailing for a while. Last year, Microsoft put the two Lumia 950 phones on buy-one-get-one-free fire sale—a pretty good sign it was having trouble moving them, much like Amazon’s fire sales on the Fire Phone. And in the last few days, HP killed off its Elite X3, one of few remaining Windows 10 mobile phones. Windows mobile has only been able to muster a 1.3% US market share. Only Blackberry has a lower penetration (at 0.3%).

Microsoft has discovered what Palm and Blackberry already learned, when they waited too long to replace their aging last-generation operating systems with something newer—there’s simply no room for a third player in a mature device market already being dominated by two major names. When you come in that late, you simply can’t get enough users to get the chicken-or-the-egg network effect off the ground. Users won’t buy in when there aren’t enough apps, and app developers won’t buy in when there aren’t enough users. Microsoft’s domination of the desktop simply wasn’t enough to translate into a user base for its mobile platform.

Of course, that’s not the only reason, and previous versions of Windows mobile have had greater degrees of success for a while—the Ars Technica article mentioned above has a great overall history of mobile Windows’s modern (post-iPad) incarnations, including a number of mistakes it made that may have squandered the operating system’s user base and contributed to the brand’s marginalization. But overall, there just wasn’t enough there to appeal to the users who’d already committed to Android or iOS.

When I played around with mobile Windows 10 myself, on the Journey tablet I tried out and the “Kindow” dual-boot tablet I kept, I found the experience to be less than compelling. The mobile version of Windows felt as if they had slapped a mobile coat of paint over a desktop interface, but the desktop interface kept peeking through and getting in the way of what I wanted to do. It felt like I had to pair a keyboard and mouse to get any real use out of it.

It felt like Microsoft was making the same mistakes it had with the doomed Windows tablets that pre-dated the iPad: trying to cram a complete desktop operating system into a mobile interface. iOS and Android were built as mobile designs from the ground up and are a lot easier to use without keyboard and mouse, to the point where even a cheap Android tablet such as the Fire can do many of the same basic tasks as a desktop—but I have trouble getting the mobile iteration of Windows to do mobile tasks very well. And Android and iOS have already got robust user bases who are satisfied enough with their user experiences to see no reason to switch. In the end, it’s no surprise Windows 10 mobile failed to catch on.

It’s sad to see another mobile platform go by the wayside, but the fact that even desktop giant Microsoft couldn’t compete with Google and Apple in the mobile arena is reassuring for Android and iOS’s staying power. In any case, it’s clear we’re still going to have two major mobile platforms available for mobile Internet use, media streaming, and reading news and ebooks for some time to come. It’s just that neither of them will belong to Microsoft.