Buying solar power from residential users is usually a loss to the utility (hence other ratepayers). Especially when they want to sell at retail electricity rates rather than wholesale -- which is what net metering essentially does.
There's a lot of data pointing to the idea that even 'natural monopolies' benefit from competition. IIRC, Lubbock Texas has two hydro companies and Lubbock and other residents of two hydro company towns enjoy on average 20% lower rates.
There are already places that have banned internet delivery coops and places have tried to outlaw selling solar energy back to the grid.