I was just informed that
... ID questions without upvoted\approved\any answers are usually deleted after 28 days.
Now, assuming that it's a good question, the user has done their research, and there is enough information for someone who has seen the movie to answer the question (or provide extra detail), I want to know what the harm is in leaving the question around?
If there are few upvotes and no answers, the question should sink pretty quickly and not bother anyone.
There is however, a clear benefit: it can still be found on Google. Given a billion internet users and few decades, there may well be a few people with the same question, and possibly build towards an answer. This is the value that unanswered SE question provide: a single page that a handful of people with the same question across the planet and across time can find through Google.
So why remove the questions? Is it just some idea that the database should be kept "clean" or is there a real benefit to not having them lying around?