I gave up on Windows Phone almost a year ago, citing a lack of apps and Microsoft's mobile platform getting left behind.

While the app gap has always been a problem, Windows Phone is now five years old and it's still facing new challenges. Over the past year developers haven't flocked to Microsoft's platform to improve its app situation. Instead, more and more high-profile apps have actually disappeared. Mint's removal this week is the latest, angering Windows Phone fans, but it's not the first, nor will it be the last.

American Airlines, Chase Bank, Bank of America, NBC, Pinterest, and Kabam have all discontinued their Windows Phone apps in the past year. These huge apps have simply disappeared or will no longer be updated. Some companies have cited a lack of Windows Phone users, and others have remained silent, but each removal has put Microsoft another step behind in the mobile race.

It's not just third-party apps disappearing, either. Microsoft has removed several MSN apps and its popular Photosynth app, and the software maker has also killed off a number of special Lumia camera apps. Windows Phone users still don't have great Skype or Office apps like Microsoft produces for the iPhone. It's stunning that, after five years, the best experience of using Skype or Office on a phone isn't on one powered by Windows. This will change in Windows 10 Mobile, but it's not available yet.

Lumia sales are heading in the wrong direction

Microsoft's Lumia sales are starting to take a hit as a result. Microsoft sold only 5.8 million Lumia Windows Phones last quarter, compared with the 9.3 million sold in the same period last year. That's a nearly 40 percent decrease, and it's not the way Lumia sales should be heading. HTC, Samsung, and Sony don't care about Windows Phone, and Microsoft still ships more than 90 percent of all phones running the OS. Microsoft is now focusing on a "more effective phone portfolio" with "better products," which will probably result in a Surface Phone. That's fewer phones catering to the small percentage of people who still want to use a Windows Phone.

Windows Phone still has a dead app problem

Windows Phone's dead app problem also persists. Instagram was released nearly two years ago, and it still doesn't have video support. There are many other apps, like Twitter, that barely get updated with the latest features. There are third-party alternatives for most apps, but it shouldn't take Facebook two years to get video in Instagram for Windows Phone. "Facebook is all in on Windows 10," according to CEO Mark Zuckerberg, so hopefully Instagram on Windows Phone will get video support at some point in the next two years.

Zuckerberg's commitment to Windows 10 is part of Microsoft's hope that this operating system will finally turn things around for its phone platform. Windows 10 is a free upgrade for Windows 7 and Windows 8 users, and more than 110 million machines are already running the software. Microsoft is trying to create a halo effect so developers create universal apps that run across PCs, phones, tablets, and even the Xbox One. That's been the big promise of Windows 10, but we haven't really seen it in action yet.

Microsoft is also opening up Windows 10 to allow Android and iOS developers to easily port their code into universal apps. We heard a lot about this back at Microsoft's Build developer conference in April, but there haven't been any big app announcements yet. It could certainly help the app gap, but with Android and iOS dominating, it certainly feels a little too late to make a significant difference.

It's easy to blame the lack of apps on developers, but they've been saddled with a platform that is constantly rebooting. Windows Phone 7 launched as a Windows Mobile reboot back in October 2010. Windows Phone 8 then launched two years later in October 2012 and existing handsets couldn't upgrade, and apps needed to be heavily updated. Windows Phone 8.1 arrived last year, finally bringing many features lacking from Microsoft's platform. Now, Microsoft is on the verge of rebooting once again with Windows 10 Mobile.

Windows Phone has been rebooted enough

With constant Windows Phone change, the only thing that has remained persistent is a lack of apps. Windows 10 Mobile is rumored to arrive to existing handsets in December, but Microsoft still hasn't officially revealed a launch date. A lot is changing in the new OS, with different built-in apps, a new design and navigation, and Microsoft's expectation that developers will create universal apps. It's unlikely to make any difference to the fate of Windows Phone overall. It's another reset, and Microsoft can't keep hitting the reboot button forever.