We're going to edit some pages to help with that ambiguity. As I said above, we do build on desktop platforms but we don't target the QA efforts on them so it's like community supported.
https://build.crosswalk-project.org/ shows a buildbot on Linux, we're going to put public the Windows one for example. Mac OS works (I use it personally) but we don't have a bot at the moment. We don't also produces binaries atm. You also don't have the convenience of packaging your app into something that the platform can consume (.exe, .dmg...) something that Android and Tizen have. Again it's all open source, we are happy to accept patches to help on that matter.