Also, a non-content-containing signal like the weather let's you diagnose potential issues in the communication channel itself before useful information gets dropped on the floor.
If I ask you about the weather, your response gives me a chance to calibrate before we start sharing important information. For example, I may discover you have an accent that I need to get used to, or maybe you're too busy to talk (which you'll convey using posture and tone of voice), I can get a sense of your mood which might affect which topics I choose to bring up.
Once you realize that smalltalk is basically like a modem's handshaking process, it makes a lot more logical sense.
If I ask you about the weather, your response gives me a chance to calibrate before we start sharing important information. For example, I may discover you have an accent that I need to get used to, or maybe you're too busy to talk (which you'll convey using posture and tone of voice), I can get a sense of your mood which might affect which topics I choose to bring up.
Once you realize that smalltalk is basically like a modem's handshaking process, it makes a lot more logical sense.