This is a common question. Are cardan shafts not actually designed to compensate for misalignments?
This is only partially true.
Cardan shafts are used to compensate for parallel misalignment
(vertical /horizontal) between the driving and driven shafts.
However, they cannot absorb angular misalignment between the shafts.
Angular misalignment typically results in increased vibrations, which may cause the driven shaft to rotate unevenly during operation.
The consequences may reach from control faults to damages to the gears and electronically controlled motors.