A helmet may give a little protection, but there is a limit to that protection and once that limitation is reached, it cannot give any more protection.

This is the things about bicycle helmets and fatalities and crititcal injuries, the impacts involved almost always are beyond the limits of bicycle helmets. That's why there hasn't been a corresponding drop in critical injuries and fatalities with the rise in helmets use, the impacts involved are far beyond the limitations of helmets.

So go ahead and wear your helmet to prevent minor injuries, just don't expect them to prevent major ones.