Especially, because it is a collective voluntary process. I love it more than Linux (for one thing I don't use Linux). I do resent the Wikipedia for one reason -- it makes it harder to impress people with extensive pointless knowledge -- everyone who can look things up in the Wikipedia is astonishingly knowledgeable by the standards of say 2000. I know people who similarly resent spell checkers.
The amazing thing is that the Wikipedia is fairly reliable. I now know of two errors in the Wikipedia. The first was in the article on "Ricardian Equivalence." It was asserted that, if there is Ricardian equivalence then, like a temporary tax cut, a temporary increase in government spending does not cause an increase in nominal aggregate demand. Since full professors at top universities made the same howler, it isn't all that shocking. But I was alarmed.
Now I have found another error in the Wikipedia. I quote from the article on the Arrow-Debreu model
In general, there may be many equilibria; however, with extra assumptions on consumer preferences, namely that their utility functions be strongly concave and twice continuously differentiable, a unique equilibrium exists
This is false as is obvious to anyone who clicks the link in the later sentence
"(See also the Sonnenschein–Mantel–Debreu theorem.)"
Nothing is perfect, but the Wikipedia is wonderful.
I added the text in square brackets which you might find between the two quoted sentences. This is my first contribution to the Wikipedia. I have no idea what will happen next.