Despite what one might think, Windows is still ruling the desktop and in a typical enterprise environment often also the server landscape.
Basically any company that isn't a software-first company is using Windows. It's clearly not a hard rule, but it's definitely a trend.
Healthcare, Insurance, Automotive/general manufacturing, Professional services, logistics, etc, etc are Windows primary orgs. For many of these companies, internal software development is a relatively recent trend (compared to their company history) so they have IT departments that hold everybody on Windows.
The word you're looking for is probably "prosaic".
A large chunk of people making iPhone apps is basically tied into the feature set given to you by Apple that you leverage to make a product on top of. Same with Android.
What's a "vertical" in this context? The article uses it as well, but also doesn't explain. This is the first time I've heard the word used this way, and it's a tough one to search for.
But here it's actually overspecified. Parent probably wanted to simply say that Microsoft has a gigantic market share in basically every industry sector.
Instead there's clearly a large market for them to be comfortable with being Windows only.