Anything regarded as "industry standard" in some quasi-niche engineering field.

I guess that doesn't count as home use. Personally, I've been on Linux for over a decade. I don't feel like I'm missing out on any "killer apps", but there's always some odd bit of software that only works on Windows - like the freeware RC helicopter simulator I use. Wine's great.

It's just the path of least resistance for most people.