But the thing I don't understand is why they don't make it possible to run a full Windows on phones that already has the Intel Atom quad-core CPU which can run

But the thing I don't understand is why they don't make it possible to run a full Windows on phones that already has the Intel Atom quad-core CPU which can run full Windows in tablets with good performance. For example the ASUS Zenfone 2 not only has the Intel CPU but 4GB RAM too. It could be just a question of having Windows drivers for the components like the PowerVR GPU.