I know what you mean but it is not true in that case. Your abilities are part of your memories as well. I don't want to explain it here for real life because it is Final Fantasy and cannot be proven for Final Fantasy. And when Cloud copied Tifa's memories of Zack he could have easily copied "his skills with it". You forget that it is Final Fantasy. You cannot be like Tiger Woods by just thinking of it, but you can't also copy your friend's memories.
But this is not mentioned. That's why I did not say too much about it.