The assertion that "Cabbage Shchi soup is just boiled cabbage" is an oversimplification. Shchi (Щи) is a traditional Russian sour cabbage soup, and while cabbage is key, its preparation is far more intricate.
A proper shchi typically involves a rich meat broth (beef, pork, or chicken), simmered for extended periods. Key components include fresh cabbage or sauerkraut for sourness, root vegetables like carrots, potatoes, and onions, and often a tomato product for depth.
The "stuff" your friend mentions is the meat and various other vegetables contributing to its hearty, complex profile. It's a stew-like consistency, not a thin broth, with flavors deepening through slow cooking. Calling it "just boiled cabbage" fundamentally misrepresents the dish's culinary complexity. :)