There's indeed a big difference between sustained psychological abuse (as in the case of people who have been in warzones, victims of violent crime, domestic abuse, etc) -- and someone who is the "victim" of mean words.
Also slander, especially where it causes professional harm, is a whole different issue.
There is a sliding scale of psychological strength. Some people are mentally stronger than others.
If being told by a stranger that you're a dumbass on Twitter causes you PTSD or hurts as much as physical violence, that means you're a weak person, relatively speaking.
There reason we protect children is because they are weaker and more vulnerable while they grow up.
Adults need to grow up and out of that weakness and vulnerability or else they remain children.