Muscle Milk is one of if not the most popular protein supplement among the casual lifting and exercise crowd, so it makes sense to focus on it in this context. More serious lifters general do not consume their products because most of them are fairly inefficient from a cost and protein / calorie standpoint.

Optimum Nutrition's products are the gold standard for more serious lifters when it comes to protein powder. Quest bars are probably the gold standard for protein bars.

it's literally entirely about the company. maybe it's sponsored but it doesn't hide that its focus is muscle milk.