Dull coat or any serious matt or dulling spray is going to have some sort of a flattening agent in it, in the dase of dull coat its sort of yellows things. It also dulls things like metallics if you use them.
Acrylic paints should be matt right out of the bottle. Only if you add some sort of medium like a slow dry or an ink will they appear shiny.
Its to each their own, I dont say I won\'t use a flat coat some where on my models, but if they are competition I paint to avoid them.