I really do get the Linux argument and like most distros, especially Ubuntu and Fedora. However until Lightroom and PS have Linux versions I can't switch. I've tried Gimp and while it's okay, it's doesn't replace LR and PS. I've tried Darktable too and it's not a mature enough product (yet).
There's then all the issues of printer drivers for high-end photo printers and colour matching. So it's not just the photo editing software that needs to be considered, it's the whole workflow.
Did like Macs, but Apple now make crap hardware with very limited specs, so I'm stuck with Windows. I don't mind paying for productivity software, especially when I'm making money from it, but I can't see any options on Linux that would enable me to move from Windows.
The sad fact is most photographers aren't brave enough to move off Mac to Windows to get better hardware choices, so getting enough of to move to Linux to warrant the development of pro photo editing tools isn't going to happen any time soon. The tools would have to come first, and that is also very unlikely.