That phenomenon is called the "echo chamber", where you have 30 or so outlets quoting and referencing each other in a cyclical fashion rather than the other 29 outlets checking original sources. The result is like the rumor game; eventually what is said is so wildly distorted it's unrecognizable. The problem is that by outlets doing this, is you have so many people saying the same thing it lends an aura of credibility to something with very little actual fact behind it. The root cause is the 24 news cycle, where journalists are pressed to publish as soon as possible, often within minutes of the event. This doesn't allow any time at all for research, so the temptation is to skip primary sources and go to third party sources, which is either the press pool or Twitter. The reason for this, in turn, is their revenue model, which currently revolves around display ad impressions (commercials) or clicks. The clicks don't care whether your info is right. They just care that the headline is fresh and enticing.