Effective altruism is considered too demanding to be plausible. Suppose a woman can choose between donating the money she has to a charity or buying an expensive medicine for her child. If donating to charity would save five other children but her child would die, under the theory’s impartial perspective “the lives of five children outweigh the one life of [her] child.” 
If the lives of family members are universally accepted to be of more priority than the lives of strangers, then this directly conflicts with effective altruism’s first premises. Critics reject the suggestion of universal moral duty, given the subjectivity of morality and recognized complexity.