What did I say that "isn't true"? I said that (a) it's the seller's responsibility to pack the item with due care, and (b) it's a good idea to insure all packages, to protect the seller as well as the buyer. Nothing you said contradicts that. Indeed, if you hadn't purchased insurance, the buyer might be suing you instead of FedEx.

If you're saying that insurance is no guarantee that a dispute will be avoided, I would agree. Sometimes insurers deny responsibility. But it's better to have it than not.