Arguably a large part of the reason that Linux isn't used in offices is because MS Office isn't available. Of course it's in Microsoft's interest to keep it that way.
She didn't have to know anything about linux to use it. The same is true for a lot of people. More so in a corporate environment with dedicated staff to handle the harder problems. Hell, most people in offices could get away with a Chromebook and Office 365 today.
Of course, general use laptops and proper linux support are not things that are very common. That part truly sucks. And, yeah, it's not pre-installed for the most part except for some boutique vendors and a couple Dell offerings.
Aside:
Have had a few looks at System 76 lately. May change out my mid-2014 rmbp next year. Unfortunately it's one of the last systems with NVidia, and the metal 2 support for the 750M doesn't work well at all. I'm also probably going to change my desktop to Linux in a few months. Hackintosh support is all but going away, and although I could change out my GTX 1080 with a next gen Navi for hackintosh, but I just don't want to support the mac platform anymore, and my 1080 has a lot of life left in it.
It only really breaks if you want to customise it (or your hardware is badly supported).
They have the right idea today, embrace server-side Linux with .Net Core, and soon, .Net 5. That's what Linux is primarily intended for, it's a server kernel and where the action is in regards to that ecosystem. There's a reason some of the code in X11 hasn't been touched in 20 years.