When people criticise Wikipedia, they often cite specific errors in articles as evidence that its overall quality is poor. The irony in this is that it encourages Wikipedians to fix those exact errors.
While the day and month of Hamilton's birth are known, there is some uncertainty as to the year, whether it be 1755 or 1757. Hamilton himself used, and most contemporary biographers prefer, the latter year; a reference work ought at least to note the issue. The Wikipedia article on Hamilton (as of November 4, 2004) uses the 1755 date without comment. Unfortunately, a couple of references within the body of the article that mention his age in certain years are clearly derived from a source that used the 1757 date, creating an internal inconsistency that the reader has no means to resolve.
I think McHenry underestimates Wikipedia's readers, and I suspect that when people notice inconsistencies they are smart enough to refer to other sources. At any rate, the article now devotes an entire paragraph to the question, including two citations. McHenry acknowledges this problem in a later essay (while criticising a different article):
By the time you read this, the entry will likely have been corrected, and some Wikipedians will proclaim this as another proof of concept. It does not occur to them to wonder how many people may have come upon that entry in the more than three years it has existed and relied in some way on the misinformation in it. They nearly got me.
He was right about one thing: the error in the article was fixed that same day. But I think this says something positive about Wikipedia: that it is willing to acknowledge mistakes and try to fix them as soon as they are discovered. For as long as McHenry continues to points out errors, there will be Wikipedians on hand happy to fix them.