IME it's not weakness. People just don't smile without a reason. And meeting or talking to a stranger is not a proper reason.

>>The virile ruler, the vodka, the endless mounds of sour cream—they are pleasing to some. It’s just that grinning without cause is not a skill Russians possess or feel compelled to cultivate. There’s even a Russian proverb that translates, roughly, to “laughing for no reason is a sign of stupidity"