udemy reviews

There must be controls, conditions and a system for reviewing the courses by the students
any review impact on the rest of the students opinions even if someone start learns alphapatical review content of expert in the field and I notice paid campaigns to give bad reviews due to the competition between instructors and raise others
imagine some students gave my professor bad reviews and he has many articles and many scientific researches quoted by other researchers and professors and has higher academic degrees from many universities actually i'm shocked any one can write what he want
the student should know he rate his experience and his learning advancement not the lecturer
the lecturer should evaluate the student not vice versa
also some students leak content on other platforms for his personal gain and ask punch of questtions not related to the course goals to know answers these questions he might be asked from his followers he has no right to do so
let me know your opinion