GPP?

If I understand the definition correctly, if I put it in layman's terms, it seems it just means that someone is "generally" in good all around shape. They have a reasonable amount of strength, endurance, and work capacity, and they are ready to go at any time. And this should not be confused with being excellent at more than one different thing (which would be ignoring the said principal). As an example, a good powerlifter who is in good shape (has good GPP), should also be able to get around pretty well and do other things without a problem.

So here is my question. Should GPP make a difference if someone is going to be able to do good at their own sport or to try another one?

The reason why I ask is that it seems if I am correct, GPP would help just about anyone if they don't already have it. I do have other reasons for saying so. Exercise in general is good for the immune system and it makes you happy. The use/disuse principal also comes to mind here because if you aren't using your body for general purposes, it won't be good at anything.

Also, if I am correct, this might also be a good reason why for anyone to get out and do something or spend some extra time in the gym if they would be relatively sedentary otherwise. As an example, I have seen good results in the past with less time spent in the gym. But with guys I've known who worked out 5 times per week for example and included both strength and endurance exercises, they were able to jump right into sports such as powerlifting or strongman without a problem.

Perhaps the guy who spends less time in the gym, gets ok results, but then gets whipped and blames it on overtraining, but in reality he is out of shape, but. But the other guy who spends a bit more time in the gym, perhaps he doesn't get tired as quick and he ends up doing better because he has done the work to be in good shape.

Anyways. Is this correct?

I'm confused

There's a lot in what you've posted here. Several questions...I'll just throw in what I can and maybe it'll be of use to you, maybe not. Louie Simmons advocated GPP work in part as a form of active recuperation. I can see GPP as useful for hypertrophy training for some athletes. I think that if you only have so much recovery in you, and so much time to train, that you have to be careful with the GPP work. Something Christian Thibaudeau calls the finances of training comes to mind here. Is the GPP going to take away from what would otherwise be done to prepare you for your sport. Good luck to you.