The point isn't to delete bad content. The point is to delete content that is known by so few people that it is unlikely to get the attention needed to become a good article.

To put it another way, even if someone writes a really, really good article about their neighbor's dog Spike - complete with genealogy down to Rover the fifth, the harrowing near-death encounter when that gallstone removal surgery went wrong, and even a detailed account of that incident last Wednesday when Spike wet the carpet, there are so few people who know anything about that dog that it's impossible to fact-check the article. For all anyone knows it's all made up. So the line has to be drawn somewhere, and there need to be clear policies for it, as otherwise, well, things like this happen.