Why is it important to keep away from the doctrines of absolute self and absolute non-self?

There are two doctrines. Existence of self and existence of no self. Existence of self means eternalism. Existence of no self means nihilism. If self is eternal then there is no escape from suffering. If there is no self then there is no meaning of good deeds and bad deeds. There is a middle path. Depending upon ignorance , volitional formations arise,depending upon volitional formations ,consciousness arise , depending upon consciousness , name and form arise, depending upon name and form, six senses arise, depending on six senses , contact arises, depending upon contact , feelings arise, depending upon feelings , clinging arise, depending upon clinging, cravings arise, depending upon cravings,attachments arise, depending upon attachments , becoming arise , depending upon becoming , birth, ageing , death and whole mass of suffering arises. My question is: Why is it important to keep away from the doctrines of absolute self and absolute non-self?