“It’s all about the ecosystem.” That’s a catchphrase much bandied about these days. For mobile device manufacturers, having a range of quality software is as important as the hardware. Perhaps even more important.

Two companies, Finland’s Nokia and Canada’s BlackBerry, are learning this the hard way. Both make excellent hardware — they always have — but both are having a terrible time selling it. The problem isn’t the phones, but the ecosystem that underpins their operating systems: in Nokia’s case, Microsoft Windows Phone; in BlackBerry’s, BlackBerry 10.

Though both BlackBerry and Microsoft make much noise about the large number of applications in their respective online stores, the fact remains that too many key apps are still available only the iPhone and on devices powered by Google’s Android software.

Take Instagram as an example. What began as a niche image-sharing service became one of the great success stories of the app era when Facebook snapped it up last year for a stunning US$1bn in cash and shares.

Even when it was available only for the iPhone (it’s now on Android, too), Instagram was hugely popular. Once it began appearing on Android devices — and integrating more tightly with Facebook — the growth accelerated.

Instagram has become something of a marker for mobile platforms. If its developers create a version for a particular platform, it’s an endorsement of that platform. Instagram’s nod means a platform has reached the sort of volume and is likely to enjoy the sort of longevity that makes it worthwhile expending resources on it.

Nokia has been trying to curry favour with Instagram, going as far as blogging about how much the Finnish manufacturer would like to see Instagram on its top-end, Windows Phone-powered Lumia range of devices.

On Tuesday, Nokia used a launch event for new Lumia Windows Phone devices to advertise its new partnership with Instagram rival, Hipstamatic, and its social service Oggl.

Functionally, the two apps may be similar, but there are two glaring problems with Hipstamatic. It’s a paid app with further in-app purchase options, while Instagram is free. And it’s not Instagram.

These are by no means minor problems. Both limit the scope of Hipstamatic’s appeal and reduce the likelihood of someone trying it on a whim.

Nokia’s desire for Instagram’s approval is telling. The company has admitted that the most frequent complaint from Lumia customers is about missing apps. BlackBerry has run into similar criticism about its new platform.

Nokia can always hope other hardware manufacturers will step up their focus on Windows Phone devices because volume incentivises developers. BlackBerry, however, will have to generate the volume itself, unless it opts to licence its operating system to third-parties, which, it must be said, is not impossible after Tuesday’s surprise announcement that it was making BlackBerry Messenger (BBM) chat available on iOS, which powers the iPhone, and on Android.

Apps have come to mean as much to consumers as mobile hardware. Even when similar or equivalent services exist, users don’t want to have to change apps because they’ve changed device manufacturers. They expect everything to work on anything, and who can blame them?

Apple has remained a dominant force in mobile despite an ageing operating system, in large part because it has the most mature and comprehensive selection of apps. It has a great ecosystem.