1) First of all, you sound like a knowledgable person. In your case, you already know what to eat. So for the tracking part, Sophia will offer you convenience mostly. But she can also detect patterns and provide insights. Things like "I notice that during the evenings you tend to overeat. How about you try XYZ to improve that". Or you could ask directly questions about your journey or even projections ("When do you think I will have reached 67kg based on my weight trend").
In general though, you are right: for someone knowledgable and disciplined enough to track meticulously and eat standard meals, a calorie tracker is less useful. The discussion and statistics part remains relevant though
2) For people we are not so advanced though, it helps both by helping them understand things better, but also flagging things: lets assume an inexperienced user underestimates what they are logging. After some time, Sophia will pick up that the trend is not moving towards the right direction and will make suggestions based on what has been logged: is the user not logging everything? is the user hitting their targets in the app and still gaining weight? are his logs wrong, is his estimated activity levels wrong etc