The point is that, unlike velocity, acceleration is absolute in GR.
If we're both moving towards each other at constant speed, it's perfectly equivalent to say that I'm moving towards you and you are stationary, or to say that I'm stationary and you're moving towards me, or that we're both moving towards each other relative to some outside observer.
The same isn't true with acceleration. If we're in the same scenario and I start a rocket thruster, then I'm experiencing acceleration and you're not. Our relative velocity towards each other is increasing, but it would be wrong to say that I'm stationary and you're accelerating towards me.
So, if you fall from a plane, your relative speed towards the Earth's surface is increasing. But it's not you who is experiencing acceleration, it is the Earth, and the difference is measurable in principle.
This is similari concept to how when something is moving in a circle, it experiences an acceleration towards the center of the circle, but this is often experienced as a "centrifugal force".
If we're both moving towards each other at constant speed, it's perfectly equivalent to say that I'm moving towards you and you are stationary, or to say that I'm stationary and you're moving towards me, or that we're both moving towards each other relative to some outside observer.
The same isn't true with acceleration. If we're in the same scenario and I start a rocket thruster, then I'm experiencing acceleration and you're not. Our relative velocity towards each other is increasing, but it would be wrong to say that I'm stationary and you're accelerating towards me.
So, if you fall from a plane, your relative speed towards the Earth's surface is increasing. But it's not you who is experiencing acceleration, it is the Earth, and the difference is measurable in principle.
This is similari concept to how when something is moving in a circle, it experiences an acceleration towards the center of the circle, but this is often experienced as a "centrifugal force".