Facts

No, not any more than eating anything else at any time of day helps with weight loss. Time is a human invention, an abstract concept. Your body doesn't know or care what time it is when you eat your food - you don't have an Off switch, your body is constantly burning calories at some rate to keep you alive. You can gain weight eating oatmeal if you eat enough of it, at any time of day.

Oatmeal is a popular breakfast among the diet and fitness set because it's inexpensive, it can be very nutritious and filling (so you don't get hungry again as quickly), and it's very flexible in terms of what you can put in it to flavor it. If you like oatmeal, eat oatmeal, bro. Just, you know, log your serving (and all your toppings), watch your portions, stick to your calorie budget. Same as with anything.