Contribution Word Count

Why does the contribution rule state that a minimum mandatory 600-word count is required? I've read plenty of shorter reviews; many are brief paragraphs or a few words - including the newest ones. It's as though we're asked to spend an hour or two writing an essay. Readers look for general impressions, not a life story. If people want in-depth, they can read the 100s of online reviews in every type of web publication.

Very discouraging and time-consuming.