I think software compatibility and power supply are two major issues. Non-x86 boards generally only run manufacturer supplied outdated Kernel, and x86 units are

I think software compatibility and power supply are two major issues. Non-x86 boards generally only run manufacturer supplied outdated Kernel, and x86 units are often only compatible with included AC supply. Devices that solves both of those problems tend not to be price competitive with Pi, and many ends up paying for a Pi.