They say "anyone can edit" but some entries are closed. Sometimes people stick in lies, which take time to find and fix. The authors are not experts.
But she can't argue with the math. Wikipedia is now the third most-popular information site online, ahead of CNN, ahead of Yahoo. Ahead (although she won't t say so) of The New York Times.
One other point Hafner hesitates to make, but Wikipedia is also trusted. When "revert wars" break out, administrators step in. Mistakes (like the notorious one on John Siegenthaler) are fixed when found, or when reported.
But the important math is this, and it's profound. No silo, no matter how big, can deliver more information bang-for-buck than a community working together. No single company, no single university, could have created Wikipedia, which has only been around since 2000.
The story comes down to one paragraph in Hafner's piece, concerning founder Jimmy Wales:
Six years ago, Mr. Wales, who built up a comfortable nest egg in a brief career as an options trader, started an online encyclopedia called Nupedia.com, with content to be written by experts. But after attracting only a few dozen articles, Mr. Wales started Wikipedia on the side. It grew exponentially.
I think this relates directly to the ecology of open source licensing schemes. Many businesses, and businesses new to open source, express a preference for BSD-type licensing. But the projects embraced by communities, under the GPL, seem to move forward faster.
If you want to control your code, under open source, BSD licensing probably is the way to go. But you may end up like Nupedia. If you want to grow exponentially, you need to give the community the same rights and obligations you claim for yourself.