I was going to post roughly the same thing. Data service is not defined by the number of u's. It's by the service you get out of it.
I can't imagine having racks in my house unless my full-time career is intensive hacking. Otherwise, I'm just nerding out, wasting boatloads of power, and filling my house full of noise and heat in order to show chicks how incredibly sexy I am with my racks full of linux boxes and hubs and UPSes and whatnot. Ahem.
A single Mac mini is an amazing home server. It's the hub that my more portable devices check in with or rely on. And it's all I need, and more. It is shitloads more powerful than a rack full of computers I admin'd a decade ago, so why would I need more?