Back in the days of radial lacing it was a common sight. Some hubs couldn't handle the loads on the flange. The mix of head in/out seemed to help even it out. In the end I don't know that it wasn't just a case of hub defects that started the rumor.
Heads in does provide more triangulation, but you have to be a bit more diligent in seating/bedding the spokes at the time of build
Heads in does provide more triangulation, but you have to be a bit more diligent in seating/bedding the spokes at the time of build