Pre installed hardwares. It's not just about "being easy to use" or "working software X". 90% of the users are not going to install Linux themselves, because they have no idea that Windows is something that can be replaced like any other softwares.

Even then, they'd not just begrudgingly use Linux because it was preinstalled. They'd find tech support and complain about how everything's just completely changed and they want their normal PC back.

So no, Linux desktop will stay niche no matter how it gets, at least for a long time. Something as braindead simple as ChromeOS may help though.