Wall plugs need brick, block or concrete to hold well. Plaster just will not do, because it has minimal holding power. It’s usually way too soft you see. Sure, if the wall is plastered with hard cement render and thin skimming coats, you might get away with some light to medium loads, but generally the plastic plug needs to be pushed into the wall itself so it’s entire length is into a brick, a block or concrete etc. Why? Because the way a wall plug works and holds in place …
