Even with proper training that is personalized to their weaknesses? Really? Is there some sort of physical handicap we are leaving out?
It's difficult for someone who has some co-ordination and physical skills to realize the limitations of those born without. Maybe I'm holding the achievement of a GM card at too high of a level but I've worked with people who just struggle to do the things that are easy for others. That's one reason every great shooter can't be a great coach, they may not understand the limitations some us have to work with because they didn't have to themselves, so then they don't have the answers that would help. I fully understand the "fuck limitations just do it" mindset but there is a brick wall somewhere waiting to stop us, it's way further up the food chain for some and a lot closer for others.
The ability to think on your feet is something I don't think you can teach, there are times in our sport when that can make a big difference in outcome, of course I'm talking about actual match performance not shooting classifiers which really is just shooting a drill. I've known several people who just couldn't get it, maybe it was physical maybe mental, but for instance shooting a sub 6 sec El Prez was something that just wasn't going to happen.