Why the need to track footage?

Since all phones and professional cameras have a gyroscope that tracks the exact motion of the camera. Why can’t this information be exported out and just use the data that is already in the phone (camera). No need to motion track anything.

Is this complicated to do? I am in the process of learning programming (Python) and I was thinking I would try to take this on as a project. Maybe and app that can export this information for 3D programs.

What am I missing? why isn’t it done this way?

Inertial sensors aren't precise enough over time.

They drift and this error compounds.