But if users don't care, why do platforms care? Maybe it's actually a reliable signal? Obviously it's also more reliable in the context of other evaluations by

But if users don't care, why do platforms care? Maybe it's actually a reliable signal? Obviously it's also more reliable in the context of other evaluations by the same reviewer which the platform has easy access to, i.e. if someone always gives 5 stars, then a 4 star review from him is much worse than one from someone who never gives 5 stars.