Low-effort content mills will never, ever care enough to generate more accurate, consensus-based output, especially if it adds complexity and cost to their workflows.
> That kind of structure seems more scalable than adding disclaimers after the fact.
Not if your goal as a business is to churn out slop as fast and cheaply as possible, and a whole lot of online content is like that. A disclaimer is warranted because you cannot force everyone to use the kinds of approaches that you're talking about. A ton of people who either don't know or don't care what they're putting out will inevitably exist.