It doesn't stop specialized malware, but it stops clipjacking. Security isn't an absolute. You're not trying to stop all vectors, you're just trying to put up

It doesn't stop specialized malware, but it stops clipjacking. Security isn't an absolute. You're not trying to stop all vectors, you're just trying to put up a barrier to trip up by far the most common and easy method. In a world where everyone leaves their doors open all day, you're asking "Why shut and lock your door when an attacker could just smash your windows?"