Relying solely tradition means you can’t make up new bs every generation. Look at the difference between 3rd Century and 9th Century Christianity. Both bizarre and neoplatonic but in completely different ways. That’s why sola scriptura (and by extension the entire modern historical/critical mindset) was formed, the world needed orthodoxy, continuity, stability from generation to generation. It worked but the result for the branches of Christianity that adopted it is something far more dry than what came before.
Discussion
solely on written tradition* sorry this one went through a couple of drafts.
Relying solely on written tradition locks you into a singular path and prevents the adaptability necessary over said generation. Standing still is stagnation and stagnation is death. You're supposed to make new shit as you go along based on the changing requirement and challenges faced by said generation. Tradition is supposed to be fluid a guiding, but gentle hand. As some traditions lose their purpose as the context around them changes.
Written tradition doesn’t mean there can be no new tradition, it means the existing traditions can’t be perverted. When you say it should be fluid, do you mean we should lie? Or do you not believe our traditions are true to begin with? If so, what use are they, besides being fodder for enthusiasts?