Humans are not in any way homogeneous, though. So, not only are people not necessarily all incapable of accepting criticism, those that are will have different reasons for it.
Though, based on this comment, it seems you’re dealing with people who don’t like it when you don’t universally massage their ego.
In which case, those specific people you’re thinking of have tied their self-worth to their perfection. Tell them they’re not perfect and they get tetchy.
They are?
You may want to define your terms: what do you mean by “afraid of criticism”? Which humans? Why humans and not “people”?
Who exactly is afraid of criticism? What kind of criticism? Surely not everyone is afraid of all criticism?
Humans is a term to explain the whole of humanity in an unbiased manner. And in my perspective, humans as a whole are short of humility.
Humans are not in any way homogeneous, though. So, not only are people not necessarily all incapable of accepting criticism, those that are will have different reasons for it.
Though, based on this comment, it seems you’re dealing with people who don’t like it when you don’t universally massage their ego.
In which case, those specific people you’re thinking of have tied their self-worth to their perfection. Tell them they’re not perfect and they get tetchy.