This ignores the problem of bias by ommission, where an editor merely doesn't include something that goes against their bias. This is impossible to solve with s

This ignores the problem of bias by ommission, where an editor merely doesn't include something that goes against their bias. This is impossible to solve with sources because editors still need to be able to choose to ignore something they see as unimportant. It also ignores that the degree to which a sources "credibility" derives from your agreement with it, and therefore its political bias. When a source you agree with says something wrong, this is seen as an honest mistake, but when you disagree with them, it acts as a tarnish on their credibility forever more. Wikipedia editors can use "credibility" to prevent others from correcting their ommissions.