Agree that stand up locking is easy to learn and difficult to apply. People can learn 20 different locking skills in 1 hour. It will make people to feel good about themselves. The successful rate is always low if your opponent has Peng Jing. There was one CMA master who gave a demo on the stage and challenged everybody who could apply any locking on him. Many audience got on the stage and tried, none of them could apply locking on him (of course none of the audience knew how to apply locking combo - use one move to set up next move).
This thread only discuss the "risk" and not how often it could happen. Even your locking may not work on your opponent, that locking may put your opponent in defensive mode. Your opponent may lose "先机(Xian Ji) - dominate situation" at that particular moment. It's like your foot sweep may not take your opponent down. But when your opponent tries to escape your foot sweep, he may forget about attacking you. That's may be all you want - to put your opponent in defense mode at the particular moment.