alt Hacker NewsForever soup isn't new, of course.
Poor families do it to cheaply make long lasting meals.
My late maternal grandmother used to have a pot of forever soup on the stove, and she would put whatever she had on hand in.
Spare ribs, check. Leftover veg, check. McDonalds fries, gross, but check.
One of my grandfather's favorite jokes whenever we visited was to yell across the house that guests had arrived, and to add some more water to the soup.
Of course, my grandmother was a farmer all her life before I was born, so she was always making far too much food (nobody ever left hungry was a mark of pride) but it took some growing up before I really contemplated the kind of life that joke would have come from.
And yes, always had soup going.