Whether or not you need to soak breadcrumbs in milk when making meatloaf depends entirely on the recipe. Soaking dry breadcrumbs before adding increases the amount of moisture in the meatloaf, keeping it from drying out. For this recipe, I don’t think it’s necessary, because one of the key ingredients is ground pork, which, together with the other wet ingredients (milk, tomato purée, egg), adds more than enough moisture.