There is a reason for that called Microsoft Office. And Photoshop. And a million other niche applications that are Windows only (I work with scientific lab equipment) because not enough people wanted or cared about Linux support. Heck, companies selling hardware to labs will bundle a free Windows workstation rather than port their complex app to Linux.
And no, Libreoffice is not good enough if you are a person who uses Office specifically rather than any random Word processor. Writer is ok. Calc is incompatible with Excel, and Impress is just inferior to PowerPoint. The activation barrier to switch is not worth the 60 bucks Microsoft charges a year for their suite. 60 bucks is what a professional who uses these apps earns in 1 hour.
FOSS people need to understand that FOSS is not a selling point. Superior software is eventually what people will use, irrespective of its FOSS nature. Linux is in the unfortunate situation of being the superior OS with inferior application coverage. Too bad the only thing people use the OS for is to run applications.