You are also missing the cost of the distribution and transmission infrastructure, which distributed generation avoids in addition to the transmission losses
That's because of unpredictability of these power sources.
With centralized generation you can do hierarchical network, with smaller capacity further "downstream".
With distributed you need P2P network, and when some part of country has no sun and no wind - you need to be able to get that energy from other sources.
Distributed storage changes the game, but it depends on the costs.
6% includes ALL losses for the entire distribution infrastructure. I am explicitly not missing that.
You also have not cited any evidence supporting your claim, so I don't know why I bother.