So, MongoDB with a file URL? (Hint: that's you could implement the MVP of this, and if you use a URL you can even reference user files they don't store locally)
And file permissions are dead? Because nobody has kids that use the same desktop they do?
This is (from a technical standpoint) the silliest goddamn thing I've ever heard.
From a product standpoint, you could probably pitch and get a few M. Why the fuck not.
What you said about a glorified metadata search is right on.
Some people share devices, but most people we share with use other devices.
I'm glad you think its silly because all great things have haters (bitcoin, justin bieber, etc.)
Many modern filesystems are littered with the reeking remains of attempts at supporting metadata (for example, NTFS), most of which nobody cares about and which just add implementation complexity.
If you want to pitch a more useful and more abstract version of what you're describing ("how can we present searching and accessing a metadata forest backed by traditional hierarchical file stores") then by all means I'll be friendlier but right now you're coming across as a crank ignorant of the history of the ideas you're decrying.
Stupid things have haters too. Some people "hating" your idea doesn't make it good. Doesn't make it bad either.
I don't know what windows does these days, but OSX has had tags and metadata for "files" for a while. It's even easy to add the info, and search for it. I never bother though because, for me, it doesn't solve any problems or add any value.
"It's responsible for handling user metadata such as tags, rating and comments. It also handles indexing and searching for files, emails, contacts, and so on"
Cross-device research for semantic desktop: http://www.dime-project.eu/en/home/dime/project/solution/con...