Actually, no. When Stephen Colbert asks his viewers to edit some article, it's fairly simple to lock that single article. Any collateral vandalism is easily reverted.

The problem here is much more insidious: hundreds of articles are being edited. Furthermore, though the edits are of low quality and often plagiarized, they are not so obviously vandalism that bots or editors can instantly revert them.

Yes, but they aren't required to do it for college credit. They're just like any other troll Wikipedia is constantly dealing with.

Those people are probably too lazy and high to edit Wikipedia.