Seems like Linux has been competing just fine, but I take it you mean "a desktop linux that appeals to windows/osx users by being similar to them so the learning curve is small".
That seems to more be about a lack of effort and manpower, not because people are pulling in different directions but more that the people who would actually build that stuff don't want it enough to dedicate their free time to building it. That and designers don't seem to be nearly as interested in contributing to FOSS as do programmers.
Because non-technical/non-contributing users are nothing but a drain to FOSS projects. A success is having a large number of contributors, all cooperating to solve a shared problem so they can all spend more time on something else, with some of them dedicating themselves to the problem because it's interesting and helps their friends.
No one is doing it at the scale necessary for the same reason Apple isn't spending all it's money developing products for people who couldn't possibly pay for them. They aren't stupid.