When a HN user submits an article link, the intention is that people will click the link and read the article. A "bad faith summarizer" is just shooting themselves in the foot, because if the summary inspires people to read the article, then they'll immediately discover that the summary was bad. So what's the point of the bad faith summary? Your hypothetical scenario doesn't even make sense. The URL is still there. The article title is still there. Everything that's available now would still be available.
Moreover, there's nothing now stopping any commenter on a submission from giving a bad faith summary of the article.
It's just like the TV guide. You've got a long list of channels, and you've got a bunch of show names, but you don't necessarily know what the show is about, whether it's worth watching, so you read the summary. Are you going to complain about the existence of the TV guide, because it's "subjective"? Hacker News is more or less entertainment, although this conversation is not very entertaining and getting less so as it goes on.