You do have a point that if you only get news stories from one source that your perception can be altered, but I feel that is actually not entirely relevant.
I think the point you are arguing is more that if you are too selective in your viewing then things can be distorted, not watching/playing too much. On that point, I must agree with you, however, on the issue here, I cannot agree.
I play a lot of games and watch a reaonable amount of television, although to a much lesser extent as I do not have a TV license at university. I would like to think that my sense of reality is still intact, I know that games like (and I am assuming this example will be done to death, so I apologise in advance) Grand Theft Auto and the like appear to encourage people to do things that are widely agreed not to be the best of things. But in knowing that these are not real and that what is portrayed in these games and other types of media are not the same as real life allows you to enjoy these kinds of things without doing any major damage.
Until recently every single study into whether or not violent video games had a damaging effect found that there was no evidence to support this claim. Although, I do believe that recently one report said it was possible (I do not have details of this report to support this though, I am sorry)
There was also an article on the Yahoo website that suggested that surgeons who played games had better results than those that didn't, but did point out that playing excessive amounts of games can impact on other areas, such as education and social skills. (Which I would like to point out are not your view on reality, but something else)
I guess the point is, that excessively doing anything has an effect, but I do not believe that one of the effects of excessive gaming/television watching is a distorted view on reality.