The individual ponies only know what society taught them. I can understand that Celestia might not be able to just reprogram a pony, but there’s no reason society should be that hard to mold. If you just want to make sure the ponies are taught that there was a war, there are better ways to do it than fighting a war.
I don’t get the “fall down and skin their knees” part. In order to learn your lesson, you have to survive.
For a society to learn a lesson, the society has to survive.
The individual ponies only know what society taught them. I can understand that Celestia might not be able to just reprogram a pony, but there’s no reason society should be that hard to mold. If you just want to make sure the ponies are taught that there was a war, there are better ways to do it than fighting a war.