That not unlimited people can rent the same title at the same time is probably a licensing issue (as they only purchases x copies for lending).
The DRM in this case is mostly about the time limit on the rental though. If you would get access to the title indefinitely it would be giving away not renting?
The DRM in this case is mostly about the time limit on the rental though. If you would get access to the title indefinitely it would be giving away not renting?