Basically because it is bad jiu jitsu I think . I am in no way saying that it does not work , or that it is not effective . I am also not saying that it isn ' t legal in some point set ups . But just because you CAN do something , does not make it cool . Just because you are playing open guard and CAN accidentally tag a nut as you move your foot to the hip and not be penalized for it does not make it ok . I ' m not trying to say there rules telling you not to because I am not 100 % sure on that . What I AM saying , is morally , from the position of one human to another competing in something , that it is a very dick move to just pull the 5 year old nay nay I ' ll just hold your mouth and nose until you do what I want . That is a 5 year old bully move , not something worthy of points of praise ethically . However , it is also on every single person on the the mats to know to protect said things , because there are people out there in real life and on the mats no offense meant that will be dicks and do stuff like that because they can . TLDR just because you can do something does not make it less dickish .