I want this as much as you and everyone else who upvoted you, but the problem is there is no obvious business model in it. Sure, techies will pay (app.net?), but the general population doesn't care enough to put out money for this.
What I'd like to see, and hardly anyone is talking about, is the cooperative model for this. Servers run by a community of interest; paid staff to manage the things which really require central clearing (anti-spam and anti-abuse in particular) and develop the system; users paying on an ongoing basis and being given a voice and a vote in the way the system is run. Federation with similar systems.
Bits of this exist already, but only on a very small scale and with the political/organisational infrastructure - basically individuals running Minecraft servers and the like.
I suppose I could gather thousands of recruits for something like this if I said "blockchain" a lot, but in truth it's the opposite: a system that requires users to trust individual other humans.
I think it's a mistake to assume that nobody will pay for such services given the vast number of people online now. It's just a matter of appropriate market segmentation [1]. Business models emerge as people begin to use things, and we should remember that Google didn't have one for a long time (neither did Facebook).
[1] The teenage version of me didn't give a damn and only used free things but the adult version of me has a much better understanding of the trade-offs I'm making (and I also have disposable income now). I don't wish to become a sysadmin, which means I have very few options.
That's why this is really a distributed systems problem. In order for an app-developer to build such an app, the deeper problems around deployment, sync, and identity/connectivity need to be resolved. Developers just need something to target that provides the appropriate components. That's what the toolstack I previously linked is trying to solve. Without that, we're stuck with requiring someone else to provide the central system/aggregator. Clearly this is a non-trivial problem but if it can be cracked then it'll be as impactful as the opening up of the Web was.
Thinking about this, I wonder if the economics would work given the ad-supporter/loss-leading aspects of some of these services. Still, interesting.
I supposed it could be, or a UI problem....it all depends on the architecture of the code and how you choose to define the problem. Regardless, it's all certainly feasible and possibly will be done sooner or later, it's just a matter of when. Are you familiar with the Diaspora project from a few years back?