"Exiting the commercial DC power business" means eliminating DC generating stations, AC-DC substations, and the associated grid as quickly as possible, supplanting them by giving existing customers rectifiers at their place of business. If you approached PG&E after c1980 asking for DC, you wouldn't be able to buy it (still can't). However, you can buy the AC and supply your own rectifier. As the article says: " . . . today’s neighborhood-scale circuits get their DC power from the AC grid. Each is equipped with a rectifier plugged into the local AC distribution system." PG&E would not go along with adding any new customers to the "neighborhood-scale grid" mentioned in the article. New customers would have to buy AC and do their own conversion. This is what is meant by "exiting the commercial DC power business" (an industry term, BTW).