Cartographers here use all kinds of software, or no software at all with basically hand-drawn work. Some people use Paint or the lowest end software. It's not the software that's important, rather its what you can do with it. I have CC3, City Designer and Dungeon Designer, though I don't use them myself (I run a digital print company and sometimes have to print client maps created in one of those apps - that's why I have them). I don't use GIMP nor Photoshop, rather I use a vector drawing application - Xara Designer Pro 9. I am a professional fantasy cartographer, but my expertise is based on my knowledge of my software, not the software itself.

While I can agree that many/most of the maps and tutorials here seem to be GIMP/Photoshop related, as there are many users of those software, but in no way are those the only mapping applications used here.