потому что почти никто под арм не компилит
In addition to UWP apps, Windows 10 on ARM can also run your x86 Win32 apps unmodified, with good performance and a seamless user experience, just like any PC. These x86 Win32 apps don’t have to recompiled for ARM and don’t even realize they are running on an ARM processor. Note that 64-bit x64 Win32 apps are not supported, but the vast majority of apps have x86 versions available. When given the choice of app architecture, just choose the 32-bit x86 version to run the app on a Windows 10 on ARM PC.