Rather than any one OS being "better" I'd put in "right tool for the job".
Windows and other more 'managed' OS's are popular for the same reasons I mentioned high-level vs low-level languages. It's wrong to just say "windows is used when OS speed doesn't matter", because the correct response is "Windows is used when you need the OS to get out of your way and just let you do the task-focused thing you want".
Large enterprises also tend to roll out Windows desktops across their organization, and large enterprises aren't just a bunch of dummies, they have carefully calculated the efficiencies and costs involved, on a cross-enterprise level across thousands of machines and determined that rolling out Windows is the most efficient use of resources, given the entire range of factors. In context, they've determined that windows is "best". "best" is not just about how fast one box crunches numbers, it's about total resource investment and cost across the lifetime of all machines on your network. Sure, Linux wins in scaled data-centers, but it's objectively failed in winning in the enterprise desktop environment, which is what it needs to win to prove that it's a viable alternative to desktop Windows.
Windows is objectively better at being that thing enterprises need than Linux is. If Windows was only the "doesn't matter OS" as you state, and Linux was objectively better at some things, Linux would be chosen by the bean-counters in the big companies. But it ain't.
Windows or other OS's with more "hand-rails" are popular not because people are stupid, but because it's a more efficient use of the user's time to have tools that just work right out of the box and don't require you to waste time learning a manuals-worth of stuff you literally don't need to know. Windows and Mac are popular because of labor specialization, a fundamental economic principle that drives higher productivity.
Sure, everyone using Linux would be a slightly better use of computer resources but it'd be a dumb-ass approach because that fails to account for the user's time resources, so it would in fact be a comprehension fail of the big picture. People make conscious decisions to specialize their domain of knowledge. It's not a failure of the system when a large amount of people decide that learning the inner workings of their tools is a waste of time they could spend mastering their own area of expertise instead. Why should a painter who wants to use a computer learn what is effectively half a university's degree worth of computer specific knowlege needed to properly run something like Linux, when they could spend that time doing art and becoming a better artist? That's why in context, Windows is better in that circumstance.
Which is "better" is entirely relative on a case-by-case basis. It's like asking whether a screwdriver is better than a hammer. Depends on the user and the job needed to be done. Windows or Linux isn't "better" in some platonic sense, because "better" only exists relative to some need. We can say that Linux is generally a better choice for data-center scale computation and that Windows is generally a better choice for a desktop machine. That claim isn't in any way saying "Windows is better than Linux". Just, often it's the best choice.