Yes. One huge problem is slashes are also used for command-line switches. That can entirely change the meaning of your commands. For example, compare these two

Yes. One huge problem is slashes are also used for command-line switches. That can entirely change the meaning of your commands. For example, compare these two in the command prompt: start /Windows/Notepad.exe start \Windows\Notepad.exe I wouldn't blame this on poor parsing or other silly things though. I actually think it makes sense to use slashes for switches, because they are invalid filename characters, whereas dashes are valid, and hence get ambiguous (hence the need for "--" in *nix). I think it would've made more sense to disallow slashes as directory separators entirely, to avoid this for good.