I see what you're saying, and it might not always be ideal - but if they're just queued up for approval rather than published, there's scope for editing. And it's also about what people expect - if you specifically market it as 'here's our best posts, don't forget to check out the full discussion', for example, people know what they're getting. At least with my site, I think if I could get the most popular posts in front of people's noses, it'd be valuable. The occasional false positive when everyone upvotes a two word inside joke won't do much harm, and can be removed later or caught during an approval process.
There's scope for bad actors to, eg, spam reputation to get their posts onto the social media feeds, but again, it's not necessarily the end of the world. No need to let the perfect be the enemy of the "really useful, and we could have had it years ago."