I have hardware in my pocket that is hundreds of times more powerful than the first web servers I every worked on. There is no technological reason why that same hardware couldn't be used. I'd love to have a PAN based around my phone (which is way more local to me that much of the "hardward with their own databases" that I've ever worked on. Federation to Facebook/Google/Instagram/whatever the next big thing is would be amazing. And the reason it hasn't happened even though powerful hardware is everywhere isn't due to lack of technology.