Wikis were invented as a way, and are a good solution when the goal is, to crowdsource objective facts about the world.
The great thing about a wiki is that as long as one person once added any given fact, it is in the wiki.
On all contentious issues, by definition there are not too few people wanting to write about them, but instead there are too many, so this is why wikis are just not a suitable mechanism for writing about anything contentious: they're a solution to a nonexistent problem and there is no rational reason why truth about any given issue should be determined by "who has managed to edit the page last".
Of course it is possible and I hope they eventually develop into a mature democracy. Point is, it has not happened yet.