it seems more likely to me that it's for the same reason that clicking the first link on wikipedia iteratively will almost always lead you to the page on Philosophy since their conversation has no goal whatsoever it will generalize and generalize until it's as abstract and meaningless as possible
That was my first thought, an aimless dialogue is going to go toward content-free idle chat. Like humans talking about weather.
As someone who was always fascinated by weather, I dislike this characterization. You can learn so much about someone’s background and childhood by what they say about the weather.
I think the only people who think weather is boring are people who have never lived more than 20 miles away from their place of birth. And even then anyone with even a bit of outdoorsiness (hikes, running, gardening, construction, racing, farming, cycling, etc) will have an interest in weather and weather patterns.
Hell, the first thing you usually ask when traveling is “What’s the weather gonna be like?”. How else would you pack