Debian prides itself being the ‘most stable’ operating system. Debian is perfect for any server and for those who want a ‘stable’ operating system and doesn’t care much about the ‘bleeding edge’ software. But it does not mean that Debian should ONLY be used in such case where stability is the preference.
Debian users are more or less expert in Linux. Newbies do not prefer using Debian as it has high learning curve. So users of Debian are aware that Debian has stable, testing and unstable branch. It means Debian covers all types of users. Debian also has repository for non-free and proprietary softwares. It supports most of the architectures. Here, my point is, Debian is a versatile operating system and that is why it is called a universal operating system. So do not even think that Debian is only used for stability. Those of you who wants a stable system, to be precise, the ‘most stable’ system, should use Debian Stable. Now those of you who wants a system which is more or less stable and contains ‘cutting edge’ softwares, should use Debian Testing. And for the user, who wants the bleeding edge softwares and do not give a damn to the stability, should use Debain Unstable. So it is the real scenario. Debian is universal. Use it for your need, whatever it maybe.