So only people who have fought in wars can write novels about fighting in wars?
Of course not all works need to be this way, and many, many books are written about war by people that haven't been in it.
The broader point is that LLMs cannot have original experiences.
Stick a camera and a touch sensor on the machine, now it is experiencing the world.
Besides that, there is a lot of value in redigested experience. Quite a lot of history is only really examined in a larger context, where the person describing it cannot have experienced all the original events.
Implication is that virtually none of the novels ever written which include wars are actually original works, since vanishingly few novelists have been in active wars.
Maybe originality just doesn't mean much then?