For news stories, moderators can approve publishers (e.g. techcrunch.com) and then they don't need to review individual links anymore (though the ability to override this for individual links remains). Same for posts and authors.

If a post is edited to be something bad, there is still the fallback on reports and post-hoc moderation, making it not any more risky than having the local/federated timelines in the first place.

There's a finite number of publishers/authors that regularly create popular content, so the workload decreases after an initial burst.