Wikis are not really a defense against this issue, they are by nature a secondary or (occasionally by policy) a tertiary source of information. Once the source they are recoding does so does the value of that page on the wiki. From the OP:
54% of Wikipedia pages contain at least one link in their “References” section that points to a page that no longer exists.
This is an accurate point. Thanks for the correction. I think what I should have said is that the biggest one has that policy and, as a result, there is a trend of others following suit.