I think the reason Windows is so successful is because it's stable, bulletproof and easy. You don't have to burn an ISO to a USB and boot from it, partition a disk and install it. You don't have to grep grub at any time. You rarely have to use PowerShell for much of anything at all, including device management, managing services and even tweaking the registry.
The "desktop environment" is the operating system, not a seperate abstraction around it. There's no research required on what distro works best for you, what package manager is ideal, what file system to use, what window manager to use, what desktop environment to use. There's no messing with repositories either. No issues with drivers that require compiling from source, no marking an executable as "executable" through chmod.
I like Linux, but the Linux community overestimate how usable it is outside of their meta, and underappreciate their own mental model of what a computer is and how it differs from the layman. Most people want to open their laptop, double click a browser and watch Family Guy funny moments on facebook.com without having to troubleshoot PulseAudio because it's suddenly gone super quiet.