Splendid Silent Crusader Shoulders

Is there something I am missing about the 50% shoulderpad scrolls from the silent crusade? Like they havingg a working ratio lower than 50% or something? Because otherwise I don't see why people would choose to spend billions and billions of mesos on chaos scrolls.

For the same reason people use 30% scrolls on their equipment instead of 60%'s (or even 100%'s). They want more attack and are willing to pay with many more costly failures to reach that.