Because many don't seem to understand it, otherwise they wouldn't react the way they do when comments are less than complimentary. And you can be on social media (I suspect most) and only allow real people you know comment and message, so if that setting is not used then again there is a lack of understanding.
Two comments to that:That’s like saying women shouldn’t go to bars/clubs because there’s men that might spike their drink.
1) Spiking is assault, physical assault, not virtual world stuff. It is a crime.
2) Any woman who goes to (certain) bars/clubs needs to be aware of the realities. It's like the guy who crossed the road with the pedestrian lights on green and a car missed seeing the red so he got knocked over and killed. When he got to heaven he said "but I was right!", and St Peter replied, "Indeed, dead right".
PS I always look, whether driving or walking, regardless. A traffic light is not a brick wall safety fence.