You would be hard put to find a house that wasn't built exactly like the Linux Desktop is. Your general contractor (distribution) hires a variety of contractors

You would be hard put to find a house that wasn't built exactly like the Linux Desktop is. Your general contractor (distribution) hires a variety of contractors to install a massive pile of different components very few designed particularly for your house. Your analogy only works on the surface because of the odd notion of putting the component boundary at the board somehow. The difference isn't the unconnected nature of the work which is virtuous its the resources available. No general contractor does the work needed to integrate all the many any varied components into a pleasing design for free and none of the components themselves are free. This flow of resources is what funds both the creation of said components and their proper integration. Because software has zero marginal cost an acceptable Linux Desktop experience can be cobbled together from what efforts people are willing to donate and what can be gleaned from resources invested in more valuable endeavors like servers. The elephant in the room isn't figuring out how to get people to donate enough labor to make a third party OS work on every computer in the world, an impossible Sisyphean labor, its either convincing enough users to buy Linux computers for Linux support or finding some other way of getting sufficient investment for a more polished experience. In any case nobody wonders out loud how we can possibly get Mac OS to have better hardware support people just buy a mac. I submit that there is also a third option. Google "name of my prospective computer" and the word Linux.