The article is focused on how the limitations and changes made for consumption computing has affected the OS design and negatively impacted the users who actually need a desktop or laptop, either to produce or as hobby machines. If the OS is constantly changing and degrading, it may not matter that much to those who only really need a smartphone or tablet, but it has a huge impact on the rest.
Desktop and laptop sales have been dropping for years as more consumers realize that their needs can be met by a mobile device, tablet, or chromebook. Sure the changes probably don't mean much to that market, but that market is fading. Making unnecessary changes which interfere with the UI impact the hardcore users, who will be the base of desktop/laptop users in the near future.
Your argument is essentially that since the changes have little impact to those who don't care, that it shouldn't matter to the rest of us. That's pretty dismissive of a large group of users, and a rather useless observation.
Most people may move to iOS and Android, but that's a moot point since those aren't the people or the OSes that the article is about.
The OS should indeed "get out of the way". The best way to do that would be to stop getting in our faces, bc fashion.
Not on my desktop, but in a place I can find and organize them.
Not some magical mystery place that Apple wants to put them.
Rupert also fails to comment on how most people are primarily using the browser anyway. He didn't even use the word in the article. Oh, sure, it's annoying to users that the flavors of windows change over time, but chrome hasn't changed and that's fine. It's probably more of a bother to people when facebook or youtube has a redesign every few years.
And we know this to be true because the statistics support it. Computer literacy didn't continue to drastically rise as time passed. The reality is that the medium got out of the way of the message, and nobody spends time looking at windows anymore. They don't have cute sample songs bundled with the OS anymore (how will future generations discover Mr. Scruff and his record label now??), the wallpapers kind of suck, but people don't change them anymore anyway, or anything else for that matter (you can hide the Cortana search bar but everyone I know doesn't even bother to do that). Do kids these days even know what a screensaver is? Invoking 95 like it's a peak of UX is completely missing the point. Windows, and OSX, and others, will continue to trend towards becoming invisible, like air, and will get out of the way.