This is such a non-argument. They could've easily just started with text-diffs, then photo diffs. And later do doc diffs. Perhaps with some disclaimers. Heck, they don't do that for their main product, so why would they even do that for such a product. It's probably in the terms somewhere.

The reason they're not doing it is because they want a piece of the productivity pie.

They're not getting it from me. Ever.