Microsoft's core revenue is still due to market lock-in of their proprietary technologies: MS Office and Windows itself. There are other office suites out there, but nothing can gain much market share without complete compatibility for MS Office file formats: docx, pptx, etc. Microsoft produced a version of Office for Macs and that allowed Apple to grow greater than niche, but their market share was always tiny compared to Windows.

Outside of Windows and Mac, you're in Open Source land, which is great if you're technically minded and want to tinker and explore, but not much of an option for folks who just want their computers to work with the consumer software and file formats around them. Other than Apple, where are the commercial alternatives to Microsoft?

I'd be much more sympathetic to Nardella's renaissance if it meant real consumer choice. The situation is better than it was under Ballmer, but not as good as it could be in a real free marketplace.