They pieced it all back together.
It's a lot easier to burn if you shred it first.
Yes,that was my point.IIRC after the Berlin Wall fell there were large groups...perhaps West German government officials...who,after many,many hours of tedious work,were able to piece together some of the shredded documents.That's how,for example,it was discovered that about 1 in 8 East Germans were Stasi informants.
One can only wonder what the Butchers of Beijing have to hide.