Privacy is about boundaries.

A society that was fully transparent could not work.

No variation would be possible

Everything would be pulled back towards the average.

"Why are you doing it differently than everyone else expects it to be done?"

You'd also have a background cacophony.

Making it impossible for anything to stand out from the noise and create motion or difference.

An overwhelming white noise that nothing could stand out from.

In complex adaptive systems, boundaries must emerge between components to prevent this heat death of the system and allow useful gradients of potential energy.