MS Office is hardly "niche professional software." I hate it, and recognize that I can use the online services, but the reality is that I have to send, receive, and work in this application and I can't easily do it on Linux.
Why? You can edit MS Office documents fine in LibreOffice and other similar software.
I can't.
Or the same with PowerPoint.
I can't.
In a modern workspace it's not just local software running solely on just your local machine emailing around files or clobbering changes in some corporate file share.
(Also a ton of MS Office work is being done through the web interfaces now anyway. I find the web versions pretty terrible but people seem to put up with them.)