You can have your own backend that does anything you want, and is completely opaque and invisible to that oh so valued social graph, because /their/ clients don't support your magic thing.
The fact that you said "clients" instead of "apps" shows that you still don't understand the vision. App.net provides functionality that you can safely build an app on, and which is fundamentally more useful than the sandy foundations of Facebook or Twitter. That functionality is something which is non-trivial and which has potential network effects. You can use that functionality, you can extend it to something private to your own app, or you can mix and match with all the compatibility compromises that would entail. You can do all this safely without worrying that the rug will be pulled out from under you just when you figure out a magic formula that works.
In short, App.net is something with the potential to build a business on, whereas anyone trying to build a serious business (as opposed to just doing something cool) on Twitter is an outright fool at this point.
I understand the vision. But I also understand, as someone who has used app.net, in actual fact, simply porting your social graph into a new app does you no good. You still have to convince all your friends to also get that same app before they can see what you post with it. The vision only works with basic media, like text, and photos, posted in a very straightforward twitter-like way.
I'll give you a specific example: Group chat with photos. Yep, there's an app.net app that does that, and now, you can't see the photos unless you have that app. so what's the point? what's in the vision for this situation?
What group chat app is that? If you're talking about photos in patter chat, there's an established annotation for it that most clients can read and use.
Whisper, patter,
Netbot doesn't support it. I don't know of any application other than whisper/patter that does.
My basic point is, the app.net vision is fundamentally flawed. It's not just a matter of positioning/marketing. It's the same fundamental flaw that google wave had. The vision is that app.net is a protocol, but you can't market protocols to people. you can only market apps. or more specifically, you can only market specific solutions to specific problems, or some fundamentally human vision (rather than a technological one)
With the app.net vision, any app you get that happens to use app.net as a back end will be subtly and frustratingly broken in some way because there's this feature, or that feature that your friend used that you can't see, because you have the wrong app. There's no commonality, there's no ultimate app that does all the things. With twitter, at least you get a link, something everyone understands, to a webpage, read in the ultimate universal client-a web browser. On app.net you just get mysterious silence. and "oh, that didn't work for you? huh..."
app.net is the linux of social media. Nerds love it but mortals will never get on board.
Yes - if you could get access to "a bigger social graph" without risking the owners of those bigger graphs shutting down or limiting your api keys, competing with you directly after you've proved/developed a market, or any of the other "dirty tricks" Twitter/FaceBook et al. have pulled on developers.
(Note: app.net might pull those dirty tricks in the future, but at least they've got a business model that doesn't _require_ them too)
Twitter only allows you access to 100k users or so (tokens), and your business is at risk of being turned off.
or
App.net providers you access to 150k+ users growing user base. Plus an a free sign up, access to hosting for file storage, and permissive messaging.