Wikipedia's goal isn't correctness, it is to aggregate the consensus of reliable sources. Wikipedia isn't reliable because it is agreed upon, it is reliable because determining truth values is outsourced to publishers who can mostly be depended on due to the value of reputation amongst experts in the information distribution sector. Publishers have their own biases which Wikipedia will aggregate. This is still, in my experience, a better bar than any others I've come across.
They mostly outsource to a large variety of very unreliable sources and then exclude others based purely on politics, to the extent that people can't even get false statements about themselves corrected, let alone false statements about other people or topics.
There is no "they". Wikipedia can be edited by anyone.
And reverted by anyone, if the edit doesn't meet standards - like relying on an unapproved source to correct a claim.
And that's if the article isn't locked or otherwise restricted!
In practice, there is a hivemind of extremely active editors which will rules lawyer you to death if you introduce a fact they don't like.