Where they are going with this is turning the utility model into a power broker model.
There's a lot more that goes into keeping the electric grid stable than you might ever imagine!
Consider a block of homes, where everyone on the block has solar power and is selling power to the company when they get excess power. In order for this to work, they have to produce a higher voltage and "push" back on the grid, when the grid "pulls" (in the sine wave of AC.) The systems on the market today just sense how much incoming voltage there is, then pushes back with a slightly higher voltage.
Now expand to the whole block. Out comes the sun- and everyone starts pushing at a slightly higher voltage than they sense. So the systems all push 110 V up to.... oh 200? 300? 400? How many people are there on this branch and what is the stepping factor at each home? 5V? 10V? Next thing you know, the guy at the end of the block is getting his electronics fried every time the sun comes out.
So there has to be a higher level of fluidity if this kind of mass-scale distributed participation in the grid is going to happen.