When I asked “who will create Instagram’s App.net?”, I imagined an app that simply cloned the popular photo network’s features and asked users to pay for them in exchange for “not being sold” to advertisers. Dalton Caldwell, the founder of App.net, has a much more ambitious idea: build a paid social-media file-hosting service and let a thousand would-be Instagrams bloom from it instead.

The file-hosting service, which App.net launched on January 29, is a bit slippery to grasp. Is it an indie iCloud? A hybrid of Twitter and Evernote? If it’s not an app I can download and install, what the heck is it, exactly–and why should I pay for it?

“We’re providing a personal cloud service. It’s your data store,” Caldwell told me. But I already have Dropbox, so why do I need App.net? “I think about [Dropbox] for backup and the private use case,” Caldwell explained. “This is optimized for social apps.”

It’s weird to think of social networking apps as data-storage utilities, but that’s exactly what they are. The trouble–and the problem that Caldwell founded App.net to solve–is that they’re pretty user-hostile storage utilities: they lock up your stuff (Twitter only recently made user’s tweet archives downloadable), and they can stop interoperating at a moment’s notice (see: Facebook blocking access from Vine, Instagram dropping card integration with Twitter).

With App.net, you’re paying for access to the plumbing instead: your Twitter-like status messages are stored for your use, under your control, via 3rd-party interface layers (also known as “apps”) that App.net doesn’t develop and has no business incentive to lock you into.

“When these apps get acquired [like Instagram did by Facebook], users don’t get to choose how to access their data,” Caldwell says. “Now, each App.net account will get a bucket of file storage. It’ll cost the same, but you’ll be able to do photo and video hosting through that bucket. You control your content, it’s in your account, and you can programmatically give access to it in any app you want.”

So App.net isn’t really a “paid Twitter clone” at all, as some have already observed. It’s Dropbox for social media–any social media, from text to photos to videos to GIFs to…well, whatever App.net’s user and developer community wants. Why build “the next Instagram”–even a paid one without ads–if it’s still just going to silo your stuff like all the other ad-supported apps? 

“It’s a different conceptual model than having every app have its own file storage,” says Caldwell. Indeed. Buying the “backend” of a social media experience is not really buying an experience at all–at least not the kind that Instagram, Twitter, and Facebook have trained us to expect. Those experiences are what App.net outsources to indie app developers, who are free to charge for them or not.

Meanwhile, the real experience that App.net is selling is more IT than Instagram: openness and control over your own social-media content–which now includes photos and videos–“without the negative side effects of an ad-supported business model,” says Caldwell.

He has a point, because social media apps are faddish. Instagram was a big deal last year; SnapChat is now; maybe Vine will be soon. Why put your personal social-media content at the mercy of these boom-bust cycles? Why not sock it away (for a fee) on a “backend” like App.net and bolt on whatever hot new front-end user experience strikes your fancy as they come and go?

It’s an intriguing model, albeit one that–unsurprisingly–has thus far appealed more to tech elites than mainstream app consumers. I’m also skeptical as to whether decoupling the “plumbing” of social media from the “interface layer”, as App.net does, will enable 3rd-party developers to deliver truly first-class user experiences. App.net’s developer community will certainly be able to build cool things on top of App.net’s file-storage API. But will they be cool enough to pay for? We’ll see.