To clarify, the Open Container Project was started by Docker with the help of the Linux Foundation. Then other vendors were invited (including AppC maintainers). We did this because there was a clear demand for transforming a de-facto standard (the Docker format) into a proper standard (OCF), and for opening the governance of our runC implementation.

Since AppC is a completely different format from what Docker uses, starting from that would have defeated the purpose. However it made a lot of sense to invite the people behind AppC to join, so that we could all build a better spec and implementation together, instead of arguing on technical details that don't matter.