I've been relating to this set of destructions as a scholar and a historian. Documents, evidence, art is all constantly being lost and destroyed. The frantic and brief digs which happen all over the UK at least acknowledge that the ruins were there, even if the archaeologists can only take a passing glance at the material. The particular frustration in losing these particular ones is that we know they are lost, and we know that they were once available for study. I'm not a scholar of the Ottoman Empire, or even the Sumerian. But for those who are, much of the extant evidence which could feed their research has just been destroyed. Imagine if the British Library or the Library of Congress were destroyed. Imagine if the Beowulf document had been burned in the early twentieth century.
Obviously there's more than enough material left in the world for scholars to study. It's the frustration of losing something that was already known to exist, already known to be important with which I empathize. To return to never explained's example, traditions may be lost, but the knowledge that they once existed is the lifeblood of history.
(She focused in particular on the loss of cultural heritage so, to be honest, the point of my argument is somewhat askew from hers.)