Some laws define necessary record keeping for certain tasks, such as tax info. If you have been instructed to preserve documents of a given type for a given legal case, you preserve that until after discovery at the very least. You might want to preserve it longer for your own legal purposes in that case. People can also be interviewed or subpoenad. It's not about storing it indefinitely. It's about being legally instructed to store it, saying you are, and then not storing it. Google specifically said it suspended auto-deletion but didn't. Google lying is the important part.