True conspiracies of this type are rare because a controlling monopoly not only has to have total access to the supply of whatever it's selling, but also have total control over the innovation it's withholding. That's a hard set of variables to master. You do see it with video games. The abysmal upgrades from year to year of EA's Madden franchise are an example. NFL2K had undoubtedly better game play, especially at the beginning. That forced EA to ramp up their quality... which they quickly ramped down again once they secured an exclusive contract with the NFL and NFLPA, and now offer little more than roster updates with each new version.
I don't agree it applies to the media. There are endless choices for the public. No entity has control over the supply. Not even close. That means any viewing demographic that can be tapped, will. An "uneven" supply therefore would only imply an uneven demand. These examples you're offering as a counter aren't even good ones. Hardly one to one. But specifics can never make the case for a general argument that doesn't hold water.