Before answering this question, I think it appropriate to give another example of the anti-borderline problem. Now pumpkins are round, orange, of a certain size, and there are some things which you can do with them, and other things which you cannot. For example, you can bake pies, but pumpkins can't bounce. Now consider a basketball. It resembles pumpkins in certain respects.
Basketballs are round, orange, and of roughly the same size.
But in other ways, basketballs are different. For example, you can dribble basketballs, but you can't bake pies with them. So if I ask a cook to bake a pumpkin pie for me, and a couple hours later, he returns with a gooey mess encased in pie crust which smells of burnt rubber, clearly he does not understand the term pumpkin, for this is not a pumpkin pie. It may resemble a pumpkin pie in certain respects, right down to the pie crust and the fact that it fills the room with an aroma. But this thing is clearly not a pumpkin pie.