I think those parents weren't paying attention to their child, which is why their child got hurt. Just because you have your child strapped into a toy (rocking or stationary) and nearby doesn't mean you can turn your back to your child for a long period of time. If you do need to turn your back to your child for a few minutes and they are strapped into this type of rocker, recline the rocker and pull out the stand.
I have one and LO has never gotten hurt in it. My friends have the same rocker that we do and their daughter is 3 years old, now weighing 35 lbs. She uses it as her own personal rocking chair. She has never fallen forward in the chair like that.