The downside is it fragments the finite development efforts of the contributors to the point where it becomes difficult to compete with the wider marketplace.

The downside is it fragments the finite development efforts of the contributors to the point where it becomes difficult to compete with the wider marketplace. Linux is a kernel. Linux distributions target a variety of different users, and that's where the fragmentation comes from. I guess the problem is nobody really set out to build a Windows alternative at the beginning. As such they got what they set out to build, a powerful set of tools for building "things". It was never a coherent set of tools design toward making a comfortable user experience (grab a compiler from here, a windowing system from somewhere else, mash it all together). Some distributions (I guess notability Ubuntu, and projects like KDE) have tried to polish what's available into something that's a good user facing experience. With varying success. Most of the issues here likely stem from a legacy of tools which were not designed to build a consumer facing system, and a lack of resources (and desire) to build a platform for the average consumer. Others, have rewritten the userland (Android) and produced competitive consumer facing products. Others, have continued to build what (I'd guess largely the developers) want, either to service their personal of commercial interests, things like Debian/RedHat. So different distributions have targeted different users groups. I no more want to user an Android desktop than a Windows one. But I can see how Android could be far more competitive against Windows. The question is who wants to invest the resources in building that?