... if they can`t see a bright light coming towards them then they must drive with eyes closed
It's hard to judge distance when you're being dazzled.
There used to be a monthly article called "Crash Course" in one of the bike mags many years ago. By someone from the insurance industry, it was a brief explanation of police findings from various accidents.
One such case was a fatal head-on collision between a bike and car at night on a hazard-free bit of road. The conclusion was that the bike had its lights on full beam, the car driver couldn't see where he was going, braked, but it wasn't enough.