So if a woman is suddenly in a compromising position from a boyfriend or a spouse, and she pulls guard in order to apply a triangle choke, or a guard sweep in order to end up in a mounted position so that she could apply a better choke and escape, you're saying that those skills (all of which are applicable to sport Bjj) weren't good for self defense?
First, a choke isn't necessarily a sport application. It can be, but is also a self defense application, it isn't exclusive to one or the other. The difference is the context in which it is applied.
Let's examine the context of the environment in which she is attacked. Is this a one-on-one situation? If so, she has options available to her. She doesn't have to worry about a secondary attack. So perhaps she has the luxury of time and focus to place the attacker in a choke in order to end the confrontation. To better her odds though I would suggest not being so dialed in on getting the choke (as the guy was in the video offered in the sparring thread) that she doesn't take an opportunity presented to obtain an improvised weapon in her vicinity. Additionally, there have been real world attacks in which the woman had the opportunity to grab and squeeze the testicle of the attacking man which ended the attack. If choking is the best option available then apply it. If the opportunity to gouge an eye, or crushing the testicles, or jamming a fingernail up into the armpit or a strike to the throat or regaining the feet or gaining the use of an improvised weapon presents itself it should be taken. And all of these options should be trained for in regards to a self defense situation.
Again, it is situational and if one factor changes, the game plan needs to change accordingly. How readily she is able to change gears under duress/stress/injury will depend on her training.
So if a young man gets tackled to the ground by a larger person, and quickly transitions to the mounted position and places the attacker in an arm and wrist lock, you're saying that those skills (all of which are applicable to sport Bjj) weren't good for street fighting?
In this example, is placing the person in an arm and wrist lock the best solution? It may very well be the best solution, but this depends upon the context of the attack. If drunk uncle Bob tackles his nephew at the family BBQ and the nephew gets into the mounted position, as per your example, then he may only want to control the situation and not 'destroy' his uncle in front of the family. In this context, he probably doesn't have to worry about a secondary attack and can concentrate on controlling his idiot uncle without damaging him unnecessarily.
But let's change the context of the attack. The young man is alone, the large man has buddies. An arm and wrist lock is no longer his best option because it would tie him up in this position and leave him vulnerable to secondary attacks. Doing something to at least temporarily incapacitating the large man and regaining his feet to be able to fend off additional attack, or better yet, to escape the situation would be a better option.
Again, as with the above, an arm and wrist lock is not exclusive to sport. I use locks far more than I do other elements i.e. striking etc. But I do so when it is appropriate to the situation. And I train for all of the other considerations so that I have the option to use the best response.