GoogleDoc has them because it's integrated with GoogleDrive. GoogleDrive and DropBox have them for the same reason: for compatibility with the existing OS paradigm. This doesn't say much about the inevitability of the demise of folders except that Google and DropBox recognize that it won't happen for many years. But this is obvious given that Windows 8 and Mac OS X are both built on folders.

(I don't know anything about EverNote.)