If you're using Wikipedia for anything more than casual learning, then you'd better make sure that you can find another source to confirm what you find (and make sure that that source doesn't cite Wikipedia).
Sources like Wikipedia or other encyclopedias are good for beginning to understand the topic, and finding relevant primary sources.
That is kind of why it always annoys me when somebody intentionally puts an error into Wikipedia. The message that usually comes out in the media is that Wikipedia isn't that should be used for finding primary sources, but that Wikipedia can be blatantly wrong and can't be trusted.
It seems like the message most educators get and send is that Wikipedia has little academic value, when it really is great as a starting point.
Right now encyclopedia companies seem to be operating on accuracy through obscurity, believing that if they control who edits the textbook, the results would have an acceptable level of accuracy. And that method can get good results. But that also means open encyclopedias will be viewed as more inaccurate for awhile, which means the errors are more public. I'm sure that everyone has had teachers complain about the accuracy of some textbooks, but those errors don't usually make news stories.
So I see hoax edits as somewhat comparable to a programmer intentionally putting a back door or easily exploitable code into open source software. The attempt could bring up problems with the code submittal process, and I'm sure that most well-run projects would quickly fix the error. But if the media got a hold of the story, it would not help convince technical managers and CIOs to take open source software seriously.