The issue isn't kid, adult, teen, young adult, etc. Instead, telling somebody that
Its unreasonable to expect a bunch of 14 year olds to be diplomatic.
~ @WeAreNumberUno
This is unkind as it places people into groups for the purpose of placing one group lower. This is something many people do: announce that one group is inferior to another. We need to look at people as individuals, not a collection of same thinking people, as this leads to pointing out flaws in a few individuals and projecting the behavior of a few onto the entire group.