Fact is that hoaxes have always existed and have always found ways of propagating. Wikipedia, like everything on the internet, has just made it easier and faster. It is not a problem of Wikipedia, it's a problem with people in general.
Even people who work for Wikipedia tell you not to trust it [youtube.com], but to check the underlying citations.
You say this as if it comes as a shock. That's kind of the point of an encyclopaedia and completely the point of citations. If you are going to trust an entry in Wikipedia alone for anything important, you are being very foolish.
Unfortunately, while Wikipedia has to justify itself on one hand to those who demand that everything is verified before it is shown, on the other it has those who complain bitterly that new material they have added without any verification is being removed. Wikipedia cannot do both.