Most people don't think a 3 of 5 rating is "good", rather it's half-way to utter failure. 5 star ratings as used by the general public are calibrated as 5 meet

Most people don't think a 3 of 5 rating is "good", rather it's half-way to utter failure. 5 star ratings as used by the general public are calibrated as 5 meeting all reasonable expectations and no special rating given for exceptional performance. Most people don't need instruction on how to rate on this scale, they just give everybody a 5 unless something happened to piss them off.