@SmashTheState doesn’t believe that people being nice to each other enhances the probability of community survival.
I do, if I’m regularly in touch with the person, but I don’t send a card back or anything.
I like when people do nice things and are cheerful.
In my experience, most such gestures, rather than being meaningless as some assert (this conversation comes up periodically in the real world as well) are gently and nicely meant, and I like that people make an effort to connect.
It really doesn’t matter whether or not these things are “non-events” invented by Hallmark or not, because the gun is never loaded. We choose whether or not to send cards, wish someone well for various holidays or whatever.