Why do we only experience one outcome if everything branches?
The model's proposed answer is that the observer is internal to the universe and computationally bounded, and effectively "knits together" nearby branches into a single experienced history. So the branching is taken to be real underneath, while a limited observer perceives just one classical reality on top of it. This is offered as a rough sketch of measurement, not a finished solution to the quantum measurement problem.
Related concepts
Comes up while reading: Quantum Mechanics from Branching.