That's an awfully rosy look at traditional news sources. There wasn't really any fact checking going on in the lead-up to the Iraq war, for example, at least by the major papers. White House and Pentagon officials told them things, and they dutifully wrote them down and disseminated them to the public. The NYT and WaPo might have well have been on the Bush Administration payroll, for all the fact-checking they did.Online publications (including the NYT and WaPo websites, of course) have the opportunity to provide much more access to primary sources. For example, instead of writing "Saddam Hussein has a nuclear weapon under his bed, say White House officials," a web publication can link to Hans Blix's reports that there were no WMDs. Instead of writing, "Chalabi a great resources who will be the first Democratic leader of Iraq," websites have the space to incorporate alternate points of view, like "Chalabi is a fraud who would lie to his mother to depose Saddam Hussein and take over the reins of Iraq."The mere existence of editors is a guarantee of nothing. Every blogger is a de facto editor. What matters is sourcing and reputation. And there's no reason blogs can't compete on those fronts, especially once they get a real reporting staff.
You are being too specific for one occurrence. The cartoon is looking at the totality of the newspaper industry that DOES have editors and has the ability to find the facts. With things like Twitter, you just don't. This is also similar to what JTA said about leaving the news only to Bloggers, in which Dovbear said, would be dangerous. People on the web tend to be impetuous, shooting from the hip to get more hits. They generally don't have the ability for fact checking. Granted, newspapers are not perfect of course, but Twitter is a billion times worse. Blogs are bad too, because as we see, majority of blogs DON'T have staffs, and majority of people will never have staffs.