I don’t believe we behave any differently today than we did 100 or 500 years ago. In every culture, you have to hold back and aren’t allowed to be yourself. Keeping up appearances has always been considered normal. Anyone who can’t do that is ostracised and is no longer allowed to belong, because what they say affects the rest of the group. In that respect, it’s better not to belong to a group.
Let’s say we’d call this: laughing through gritted teeth.