Anyway, that is a good question you asked, one that they didn’t figure out. But if there are enough people to ask questions and search for answers, then aren’t there enough people to manage the answers? SO already had serious community effort, it just wasn’t properly focused by the UX options they offer. Obviously you need to crowd-source the decisions that can’t scale to mods, while figuring out the incentive system to reduce gaming. I’m not claiming this is easy, in fact I’m absolutely certain this is not easy to do, but SO brought too little too late to a serious problem that fundamentally limited and reduced the utility of the site over time.
Moderation should have been aimed squarely at making the site friendly, and community should be moderating the content entirely, for exactly the reasons you point out - mods aren’t the experts on the content.
One thing the site could have done is tie questions and answers to specific versions of languages, libraries, tools, or applications. Questions asked where the author wasn’t aware of a version dependency could be later assigned one when a new version changes the correctness of an answer that was right for previous versions. This would make room for new answers to the same question, make room for the same question to be asked again against a new version, and it would be amazing if while searching I could filter out answers that are specific to Python 2, and only see answers that are correct for Python 3, for example.
Some of the answers should be deleted (or just hidden but stay there to be used as defense when someone tries to re-add bad or outdated answers.) The policy of trying to keep all answers no matter how good allowed too much unhelpful noise to accumulate.
