I've been tapped on the jewels and that was enough to stop me. lol Not sure why so many people don't think it's an effective play, especially when we have seen so many professional fighters get hit there and it stopped them. It's medically and scientifically proven that getting hit there will cause trauma.
The only thing about a groin kick is that it's a target and targets can be missed. It's no different than striking at a person's face. If I miss the face then I don't say punching at the face isn't effective. If I miss then I try again. If I miss a groin kick then I just try again. But for some reason may people think that trying to kick the groin after failing to land a good hit means that the strike isn't effective. Some people think that groin strikes are a "guaranteed" fight ending strike, but it's like everything else with fighting; nothing is guaranteed and if you miss then strike again.