It is really a marketing decision on use of satellites and bandwidth that they made about two years ago - D* pushed forward to be able to provide HD lils (which are by far the most viewed channels in EVERY market) before they opted to increase the HD national channel capacity. They are far and away ahead of DISH in providing HD locals.
This is very close to true.
The only difference is that when Hughes was purchased by Fox Entertainment Group (FEG), FEG started to sell the non-core assets, such as Hughes Network Systems so that the new "DirecTV, Inc" would mainly be about television.
Part of the sale of Hughes Network Systems (HNS) involved what is known as Spaceway, which was HNS' attempt at satellite internet through the Ka-band. There were three satellites on order, each capable of steerable spots. Of course, steerable spots are also good for delivering local channels. The Ka-band is large enough for High Definition (re)broadcasting.
So, DirecTV repurposed two of the Spaceway satellites for delivering local HD channels.
This did absolutely nothing for national HD feeds. DirecTV has had the same 46 Ku-band DBS transponders for seven years, and cannot add any new DBS frequencies (or at least none that are desirable). Therefore, DirecTV would have to wait a couple more years for national Ka-band birds to be built and launched, because they already had the birds for the local channels in the Spaceway satellites.