Exactly. When my high school switched from Windows to Linux a number of years ago, I didn't have to change the way I taught office software, computer fluency, or programming, because I wanted to be "operating-system agnostic". I'm glad that students have different systems at home than at school; that gives us openings to talk about their distinctions and how they make a difference.
These days, some students are using Google Docs for their papers and other work. They don't care what OS they're using.