Why is sound design almost always treated as a side-dish to visuals? How many aps are there that have an audio-only interface with visuals as an option? I can't

Why is sound design almost always treated as a side-dish to visuals? How many aps are there that have an audio-only interface with visuals as an option? I can't think of any except assistants, but those are just trying to mimic conversation. We have the technical capability to render good 3d spatial audio on phones that could convey all kinds of information, but instead we just remake the same sound effects over and over. Where is the innovation?