> The internet doesn't really tolerate serious technical barriers stopping someone from automatically multiplexing the content from various social networks into a single read-write stream

If the legal barrier went away, and someone surmounted the "unserious" (which I doubt) technical barriers to doing that, then the content providers would go out of business. That's arguably a good thing, but I suspect many people would disagree. The problem is the profit motive and financing model for what consumers want, not the degree of decentralization. Google didn't screw up the internet; people did, by preferring what Google offers.