https://mashable.com/2015/05/18/airbnb-reviews/
people just hate giving bad feedback directly to people, and that's why its often best to take Airbnb reviews with a grain of salt. A big grain of salt.
in the new “sharing” economy (let’s be real, it’s still transactional), two-, three-, or four-star reviews are essentially dead. Reviews are either “awesome!” or horrible. Got something lukewarm to say? Don’t be surprised if that's perceived as completely negative.
In a world where bad reviews can influence future earnings or the ability to save some money, both hosts/guests will err on keeping the peace in cause of the greater good.