The flywheel is bolted to the crank flange, the pressure plate bolted to the flywheel, so it makes sense to balance them as an assembly (assuming the PP is indexed, asymmetrical bolt pattern etc.).
However, the disc lands on the other 2 surfaces differently every time the clutch is re-engaged.
How can this work?
The disc's friction part of the radial mass is so evenly distributed that a tiny balance error is harmless. If its perimeter were 3" thick or 30" OD it would have to be neutral balanced separately.

How do simple rotational and dynamic balance differ?
If the pieces were all completely symmetrical in 3 dimensions this would work, but the largest piece (PP) is probably eccentric as to weight distribution in its thickness (front to back distance) even if radially correct.
This means the center of mass is not exactly parallel to the rotational center, but mis-aligned. The PP tries to rotate on its mass axis, and introduces a new vector. Dynamic balance senses this and IDs the correction.