I wonder how much of this is due to pressure from management. How many times has a journalist said, I'm going to need x hours and $y to fully research this and verify all the details and is told "Nonsense! Go look it up in Wikipedia and have a report ready in an hour."
I've worked in market research for the past few years. There have been times when management has asked me for an answer NOW and wouldn't listen when I told them that the data needs further verification, more research needs to be commissioned, etc.
So unfortunately, strategic decisions get made on the basis of flimsy, unsubstantiated information because researchers want to keep their jobs.
I imagine similar things can happen in the world of journalism.