Wikipedia is pretty good for its specific purpose but it’s far from the promise of the open web. Wikipedia has a number of authoritarian moderators who will revert people’s changes for opaque and arbitrary reasons.

Maybe if you took all wikis as a collective then you could get something a bit closer. There’s still the matter of finding them so it’s not ideal. Then there’s the matter of ads. Wikipedia doesn’t have them but other wikis are rife with them.