1. Restriciton of movement
2. Sensory insulation—mostly sight and sound
3. Display of socially/psychologically important stuff.
As we can see, the modern stud-frame/drywall interior wall accomplishes all these things. It is solid and functionally unbreachable, blocks vision completely, and easily accommodates the hanging of pictures or shelves on its uniformly flat surface.
The result is, in essence, an invisible wall. We even spackle such walls, giving them just enough random meaningless texture to recede completely from our consciousness. In their own way, they become as invisible as the partitions of a yurt. Such walls are also thermally neutral. And finally, they are acoustically neutral, more or less eliminating echo while retaining resonance.
It’s subtle, like stage magic.