@Emilia42
It makes no sense! Especially since some hosts can still see the star ratings.
I first noticed it when a guest booked with me who had two reviews. Both reviews raved about him, yet he had a 4 star rating. I was curious in what category he received less than 5 stars and when I couldn't see the breakdown I was a little leery before he showed up. Turns out he was a near perfect guest at my house. I barely knew he was here and he left the place immaculate. He even booked with me for a second stay a couple weeks later and again, was a near perfect guest.