"Everything is an OLE server" is the closest Microsoft concept. And it is too - files on NTFS filesystems are a lot more than just files, only (nearly) no-one uses all the fancy stuff, and it's not really exposed through Explorer or CMD. You don't really need file extensions, for example, but everyone is so used to them.
The Registry arguably is no more or less sensible than /etc full of cryptically named config files and executable scripts, all in slightly different formats...
The Registry is a pseudo file system inside the file system. It is one of the reasons that Windows is so much harder to backup and restore than Unix is, because parts of it contain system state and other parts contain configuration and the whole is mixed into one big mess.
OK, but it's not as simple as that. Man fstab-sync, for example, and you'll see that your config files can be mysteriously rewritten. Or resolv.conf being dynamically modified by DHCP. /etc is more complicated than just a directory full of text files.
The Registry arguably is no more or less sensible than /etc full of cryptically named config files and executable scripts, all in slightly different formats...