There are certain inaccuracies in the above. The "shruti" are the vedas that constitute the shabd pramana and are authorless (which is quite different from being anonymous) and thus constitute eternal truths. Even though some veda mantras have multiple rishis as drashtas, they are not to be considered as the authors nor do they claim so, many of whom have different authored texts that are part of smriti (e.g. works of vashishtha). Why the shruti should be accepted and other related questions are discussed in details by our purva-acharyas. The smriti are the authored texts and so come below the shruti in the "strength" of their validity i.e. smriti must be interpreted to conform with shruti or rejected if there is a conflict with shruti -- even the words of Lord are subject to this. Normally only the writings of Vyasadeva (since he has an avesha of the Lord) and Lord Himself are considered as valid smriti pramana (subject to being in consonance with shruti). The sadagamas among the smritis are the authentic puranas, the itihasas (Ramayana and Mahabharata) and some others like pancharatra. Traditional vedanta schools accept the prasthana traya viz. Veda, Bhagavad Gita and Brahma Sutra as the flawless pramanas.
