VI, it is true that the quality of the sources in a WP article determine the accuracy of the article, ... to a certain extent.
But you shouldn't forget that the articles are written by anonymous editors, the vast majority of which are amateur researchers and writers. Some are very intelligent and diligently try to get it right; others are incompetent, ignorant fools that have no business contributing to an online encyclopedia. Finally, many articles on WP are edited by highly biased individuals and/or groups of editors with a definite agenda. Some topics on WP are controlled by these cadres of contributors as if the forum is a Multi-User Dungeon (MUD).