Wouldn’t just duplicating the key achieve the same purpose or am I missing something?

Sure I agree with that. The problem is that the comments also often include statements without sources, plain out wrong information, etc. Much of which can also be highly upvoted. So even with the context of the comments finding unbiased good news requires you to be very sceptic and isn’t always straightforward. Additionally each subreddit has its own target audience which will also inherently result in some bias in both the news that is posted as the comments on said news. But tbh a perfectly unbiased news source probably does not exist as we are all human.

Maybe not directly an answer to your question but I don’t believe Reddit was a trustworthy and unbiased news source. Hell it wasn’t even that varied imo with news mainly being about what’s happening in the US with a focus on politics. Tbh I really don’t know what a good news source would be that thicks all your boxes.