Yes this is true and I did say in my post that they can be the cause of injury in some cases, you say it has an effect on impact, but helmets are built to absorb impact and the cut the risk of huge cuts to the vital parts of your head.
Most peoples crashes are low impact, I know even my motorbike helmet is useless in really high speed, or high impact crashes, but for those oops moments they can prove invaluable.
admittedly I have ridden plenty of times without a helmet so telling people they should be wearing them is hypocritical, but posting that helmets are more dangerous than not wearing them is generally an uninformed decision based on hearsay. How many people on this forum have actually done research into it, and how many people just spout the usual crap they have seen posted with no evidence from another thread.
Decent helmet companies put a lot of time and research into making our heads protected during riding, the more money you spend on a helmet the more research that company is likely to have done, the newer technologies they will be using and the better protected your head is. Better helmets fit better, have a smaller surface area and are made from stronger materials.
Have you seen race across America with james cracknall, Did you see the state of his head after being hit by the mirror of a truck, the damage to his head and brain afterwards, did you see the damage done to the helmet.. Do you think the injury would have been more severe had the impact of that mirror been directly on the back of his skull? ..