İt still makes no sense to me since Overall rating is the most important category that appears on your listing page and influences your competitiveness and business as such. İf a guest leaves a totally positive review and 5* in all or most of the categories + complements on cleanness, hospitality etc. and 4* overall rating it can be considered inconsistent, irrelevant, confusing or biased, whatever you call it but it definitely doesn't reflect the guest's overall experience.
Our hard efforts to provide best services to guests should be evaluated in a more objective way and not left to a guests whim or sudden change of heart.