If someone else Journal of American History, bloggers, etc. made the mistake (or in the past) have put out the full http://en.wikipedia.org/wiki/Main_Page it shouldn't be our problem.
When you get a dead link to something you know is not dead, what do you do?
I go to google.
It is far unlikely that Google will get it wrong or that Wikipedia will disappear from any search engine's results.
And we should not be taking on responsibility for other people's failings, mistakes, or trying to make up for what _they_ may have written in the past. In this case, we are not our brother's keeper.
We also can't expect to hold back progress, or refuse to comply with our own standards (even if they are seemingly arbitrary), because of things we cannot control (i.e. the past, other people's writings).
That's a lack of resolve, a culture of making excuses to justify inaction when action is called for, which is unforgiveable.
Regards, Christopher D. Thieme