At some point, a derivative idea becomes so different from the original one that it’s a novel idea in essence. Just like SMS is ultimately a derivative of cuneiform tablets, and yet it isn’t in any meaningful sense.
I don't think mailing stacks of patches is that different? As someone who built this stuff it was pretty obvious to me that web-based patch stack management was a relatively small evolution over mailing lists. Tools like patchwork bridged the gap initially, and we were quite familiar with them.
