gnome-vfs2-smb package requires samba-common through a library dep libsmbclient.so.0 However, nautilus requires gnome-vfs2-smb though an explicit requires on gnome-vfs2-smb, a decision made by the packager to ensure that the runtime detectable smb support is always available when nautilus is installed to provide a perfectly reasonable and recommended default behavior for the average gnome desktop user. Some would argue doing this is bending the purpose of 'requires' field out of necessity to be used as a 'suggests' or 'recommends' field which rpm doesn't yet have support for.