The link is just another anecdote. And you can easily do a scientific study on impact injuries caused by a hammer versus feather.
The study is required because for many millenia, it was assumed that a heavier object falls faster and everybody just accepted it as a fact. It wasn't until someone did a scientific test that that was found not to be the case.
What is "obvious" to you is not obvious at all.
You can reply a thousand times over. It still does not change the fact that there is absolutely no scientific basis that supports poly cause more injuries.