commenter:
The accounts of Our Lady of Fatima would be part of approved private revelation, thus not in themselves part of public revelation, which Tradition includes. For instance they would not be included in the Catechism, which is about public revelation - Tradition, Scripture, and Magisterium. Sacred Tradition is certainly reinforced by approved private revelation, but it does not include it.
Does tradition not include widely held beliefs among the Catholic faithful, that have been longstanding, do not in any way contradict Catholic teaching, but are not yet deemed to be Catholic doctrine? As such they would not be included in the Catechism anyway, as they are not doctrine, and the faithful are not bound to believe in them.
Of course we are not bound to believe in private revelations, but can something revealed in private revelations not, in time, become doctrine?
The revelations at Fatima have had the support of the Church hierarchy at the highest level (with pronouncements and public revelation of the secrets made by Popes to the entire body of the Catholic faithful) have widespread belief among the faithful, and have scriptural backing. The revelations at Fatima were not just meant for the three children, they were meant for the entire world and the actions of the Church seems to support the propogation of these revelations.