There are home users that will need a computer and an operating system that support real applications - I am someone like that (in addition to being in the IT industry, which - as you say - seriously suggests a "real computer." Another example seems to be 4Denise, who has told us here that she (I jump to the conclusion that the "Denise" in the handle is her first name, hence the "she") is not an IT specialist but a writer that needs some real computer applications that - so far - only work on Windows, but she needs them on a *working* Windows, which seems to be harder and harder to get these days.
There are loads of home users who need email and browsing, a calendar and very little else. For most of those a computer was the natural choice in the past (either Windows by default or MacOS by choice.) They can now as easily find their needs filled with a tablet (either iOS or Android) - with or without a keyboard - have you heard of the novel "The Extraordinary Journey of the Fakir Who Got Trapped in an Ikea Wardrobe" by Romain Puértolas? He says he was bored being a border guard between France and Spain - thanks to the EU and Schengen he was seriously underchallenged, and he started to write his novel - on his smartphone! There you go!
A good deal of the reclining PC sales figures can probably be blamed on users like that. This is also the main reason why Microsoft stopped betting its business on Windows as a cash cow and is now trying to emulate the business model of facebook and Google ...
Business users - a rather varied picture, here. Take IBM, for example - when they gave their people a choice of platforms they became the largest corporate user of Macs - many non-technical (mostly managerial) staff opted for the prestigious neat looking Apple laptops. Those who needed their computers to work stuck with the Lenovo Thinkpads they had grown accustomed to - most chosing WIndows (Win 8.x and 10 were outlawed for the longest time - I suspect that Win 10 is okay by now, but updates would be driven by IBM, not Microsoft.) and a minority of "real geeks" would opt for a variety of Linux distributions.
Another story (or two, rather) - in Germany the City of Munich (München) and the province/state of Lower Saxony (" BundeslandNiedersachsen") had engaged in projects to "go open source and eliminate the dependency on foreign suppliers that won't allow insights in their products and/or behaviour." Sadly, both have since - after many years of rather successful operations - caved in to massive lobbying and are currently engaging in very expensive projects to return to - yes, it is hard to believe - Microsoft products. They will have to answer to Government auditors, eventually. The arguments for this move included the small number of special applications that could not be migrated from Windows and an alleged learning curve amongst staff members that supposedly could work with WIndows but semingly couldn't wrap their minds around the Linux desktops. Considering that a modern application landscape is built around browsers and application servers (Java, for instance) it seems hard to imagine that people wopuldn't be able to browse to their daily applications and forget about the environment - or was it the absence of Solitaire for the coffee breaks? Will we ever know?
So, the battle still rages, but the fact remains that Sun Microsystems, by making Java available, and many others by embracing it have put an alternative out there that has reduced the Windows footprint significantly. And now that Microsoft is betting more and more of its business on "stuff" they run on their own servers (Azure Cloud "stuff") they also seem to reduce their dependence on Windows servers.
Yeah, well ...