Because Android, even with all those apps is still severely limited to what you can do compared with an actual Linux distribution. Then the next problem is tha

Because Android, even with all those apps is still severely limited to what you can do compared with an actual Linux distribution. Then the next problem is that Android itself is a mess to work with, it's not designed with an open-source community in mind, the barrier is high to make it work for this kind of use case.