Fact #3: Certain shows work completely outside the ratings system.
If you're on one of the big four networks (CBS, NBC, ABC, Fox), tough luck. Great ratings are your job, whether you're part of the team making this the biggest Super Bowl ever or slugging it out in the weekly evening news ratings battle. Occasionally a network like CBS may say that the demographic aspect of Nielsen ratings doesn't make sense, or somebody at NBC will champion some low-rated sitcoms (until recently) that win the network critical plaudits. Those exceptions are rare for a reason. Major networks are mostly just too big to spend time and money going after the world's tiny nerdy fandoms.
But if you're not a ratings darling, you should strike out for the greener pastures of networks where the ratings don't matter! The CW's been coasting by on pure moxie for years, DirecTV's open arms are ready for castoffs like NBC's Friday Night Lights and FX's Damages, and premium cable channels like HBO and Showtime just want enough acclaimed programming to sell as many subscriptions as possible.
Or just head to the Internet (yes, this Internet we're on right now!), where Amazon is putting half a dozen TV pilots into production and Netflix is producing and batch-releasing new episodes of your precious, precious Arrested Development. Netflix also released an entire first season of their adaptation of the British show House of Cards last Friday, and people who checked out the first episode tended to binge-watch the series.
The Nielsen people are failing at what they do, but they cannot stop you from being entertained. The ratings system doesn't dictate a surprising amount of television, and has no impact on your ability to legally or illegally enjoy more programming options than anyone has enjoyed at any point in human history before today. So if your beloved show dies, just go get a new beloved show in a new browser tab next to this one, because