It's necessary. The anti-vibration bracket can reduce the vibration transmitted by the engine to the mobile phone and reduce the probability of damage to the camera anti-vibration module.
However, strictly speaking, it is not 100% possible to avoid optical anti-shake module failure.
The effect of shock-proof mobile phone bracket is not good, in addition to the shock absorption design of the bracket, it is also related to your model, the placement of the bracket, and the adjustment of the mobile phone brand for optical anti-shake.