Dummies don't hit back

Muk yan zhong are essential training tools for Wing Chun. As per this article by Ben Judkins:

Wing Chun students who look back to Cantonese Opera as a critical link in the transmission of their system often assert that dummies were either part of the ships rigging or were actually mounted on the specially built (and highly uniform) fleet of Red Boats.  Opera students are said to have used them in both their basic training of performance skills as well as in their pursuits of the higher reaches of Wing Chun system.  In fact, the Red Boats are often imagined as floating martial arts schools.

If we accept this, then that means that at one point Wing Chun practitioners were training on their dummies very differently from now. The action of the waves on the ship would have caused practitioners to have unstable footing, adding a small amount of unpredictability when they issue their techniques. People would have had to work harder to gain footing, let alone the necessary grounding/rooting.

I think this is why it's important to know the history of your art - you gain insights into how your predecessors actually trained.