or are completely unavailable on other OSs (many video games)
I get a chuckle whenever I realize how things have changed.
In the early to mid-80's, there was a popular mantra that the IBM PC ecosystem was for "serous work," and anything else was "just for games," which was a slap at Apple (then dominant for business, but rapidly slipping) and the other alternatives.
Today, it seems that for the majority of ordinary people, the only reason they stay in the Wintel ecosystem is for games.
Try using bi-directional text, or including equations in Docs. It is practically unusable.
Excel is so powerful that people are doing with it stupid things and than their businesses rely on them. That stuff will never work in Docs.
Office is a killer product, with extremely rich feature set that works very well. Sadly, there is nothing in the market that even close. It is the main (perhaps only) reason I still have to use a Windows VM.
For real document creation, Word and Latex are the best out there, bar none.
For detailed and powerful spreadsheet use there is nothing that compares to Excel. This coming from someone forced to use Google Sheets at a former company, after having Excel.
For me, a common use case is to receive a large document from someone using MS Office, make small alterations or comments, and send it back... while being certain that I have not changed anything else (including formatting and layout of included illustrations) that I did not want to change. Neither Google Docs nor OpenOffice currently support that, simply opening and saving a nontrivial Word document changes the layout.
But, a lot of people are forced to use office for various reasons - trying to edit a docx in Docs/Pages/LibreOffice, for example, can be really frustrating for any number of reasons (fonts, margins, etc. all sometimes break spectacularly).
So if you're using office quite frequently, windows can be very appealing.
There are many, many products that either run significantly better on windows (Office) or are completely unavailable on other OSs (many video games).
That's changing, for sure. But there's still a long tail of products that semi-necessitate windows.