Tradition includes the Bible, so your question is based on a false dichotomy.
However historically the majority of Christians were not posessed of the extreme wealth required to own a complete set of Old and New Testament scriptures; indeed for at least the period 500-1500 AD we can safely assume the majority of Christians were either illiterate, subliterate or unable to read or write the various languages in which the Bible existed (the Orthodox have always made a major effort to translate, which is why in addition to the ancient Greek and Syriac, you have from ancient times translations in Coptic, Classical Armenian, Georgian, Ge'ez, and Church Slavonic, among other languages). For Orthodox Christians who could not afford a Bible or read one, the Church read the Bible to them in the liturgy. In particular, the Oriental Orthodox tend to go all out, with four scripture lessons in the divine liturgy in addition to those associated with the Hours.
The liturgy itself aside from the scripture lessons it contains is also constructed from the relevant Biblical passages that relate to the Eucharist and the economy of salvation, so that the essential Gospel message is essentially that which is contained in the liturgical text itself, repeated at each service. This text in turn quotes the written Gospels, which in turn in turn quote earlier liturgical forms, some unwritten and others preserved in the Pauline epistles. The liturgical text also quotes these Pauline epistles and the Old Testament; the liturgy is an inherently scriptural expression of scripture (which is neccessarily somewhat self-referential). It is for this reason that the Biblical text of the services is found in the ubiquitous prayer books of Orthhodox Christians.