Trying to make sense of the recent history of the Linux desktop, I realized recently that the main perspective was wrong. The fragmentation of user share between desktops isn't a new trend -- it's simply a reversion to coding as usual in free and open source software.
That the fragmentation is happening is beyond dispute. Five years ago, GNOME and KDE together accounted for roughly eighty percent of Linux desktops, yet today the picture is more complicated. GNOME 3, Ubuntu's Unity, and Linux Mint's MATE and Cinnamon have divided GNOME's user share, while Xfce has leaped into second place after KDE, according to the 2011 LinuxQuestions.org Members Choice Awards. Other desktops have also become more mainstream -- LXDE, for instance, is now the basis for the Ubuntu variant Lubuntu.
Conditioned by proprietary software, where a single desktop per operating system is the norm, many pundits worry about this situation. Some worry about the inefficiency of the same efforts duplicated many times over, or whether such variety might discourage hardware manufacturers from supporting the Linux-based ecosystem as a whole.
The concern is understandable, but mistaken in its assumption. For eight to ten years, GNOME and KDE dominated the Linux desktop, so much so that those who started using free software in that period must be forgiven for thinking that was the norm.
Now, the unique circumstances that produced this dominance have diminished, and desktop environments have now returned to the diversity of other free software categories.
KDE and GNOME dominated the Linux desktop for so long because of the circumstances in which they began, and later because of their rivalry.
Neither was the first interface for Linux or other Unix-like systems. Window managers and proprietary desktops like the Common Desktop Environment (CDE) were widely available long before KDE was founded in 1996.
However, before KDE, widgets and applications lacked a common look and feel. Nor could they share libraries and other resources. In other words, the situation was similar to the days of DOS, and far behind what was available on Windows or the Mac. In working to provide these advantages, KDE and later GNOME were carving out a new space on the Linux desktop, like nothing that had come before them.
Given the relative complexity of desktop environments and the much smaller size of the community in the late 1990s, even GNOME might not have begun development, except for one thing: KDE's use of the then-proprietary Qt toolkit. In response, the free software community began GNOME in 1997 in order to provide a completely free-licensed desktop.
This response was the beginning of the legendary rivalry between the two main desktops. Traces of the rivalry remain today, and you can still find users of one desktop who know nothing about the other one.
But compared to the flame wars around the turn of the millennium, the current situation is mild. Back then, not only the ethics of free software were matters of passionate debate, but also related issues such as whether Debian should continue to include the then non-free KDE in its repositories.
At the time, the rivalry seemed unnecessarily divisive. A time would come when GNOME and KDE developers would try to work together to ensure cross-compatibility with organizations like freedesktop.org and joint conferences.
Still, although the rivalry might have been counter-productive in many ways, it helped to assure that, in many users' minds, KDE and GNOME were -- if not the only Linux desktops -- at least the only ones worth considering. In the middle of the highly partisan flame war, other alternatives were all too often overlooked. As early as 1998, during the Dot Com Era when the computer industry first discovered Linux, the only desktops being discussed were GNOME and KDE.
In opposing each other, the two rivals helped to ensure that other choices were rarely acknowledged, let alone considered. Throughout the first decade of the millennium, the two desktops vied closely for dominance, often exchanging positions at the top of the opinion polls, with alternatives like Xfce a distant third to both.
The Decline and Fall of the Giants
With the rivalry more or less stalemated, both KDE and GNOME developers eventually settled down to incremental releases, each group adding features without altering the basic look and feel of their software. In the short-term, this situation satisfied everyone, making most users more or less satisfied and disinclined to look at alternatives.
However, in the last few years of the decade, the limits of the existing software had been reached. Although sometimes rough around the edges, GNOME and KDE had both matched their proprietary equivalents. Leading KDE developers had begun to be interested in expanding the desktop metaphor, while leading GNOME developers wanted to implement usability theory more thoroughly.