Earlier quoted context omitted.
It looks like they want to rename the OSS version, to differentiate it from their commercial version. They're using the analogy of Fedora->RHEL. Moby = open source development Docker CE = free product release based on Moby Docker EE = commercial product release based on Docker CE.
What exactly is the difference between Moby and Docker CE?
A lot of the community understands that "docker" has gained a lot of features, but they may not understand it is because Docker is the name of an integrated product suite a company wants to sell.
These features are added because Docker, Inc. wants to have commercial offering containing a full technology stack around containerization, a community offering to attract people to their stack, and open source backing the community offering so that enterprises don't get fearful of vendor lock-in.
But other companies want to use containerization. And Docker doesn't mean anything in their context, because they only want to use a few pieces and swap the rest for their own. In fact, they are resistant against using Docker because 1. It is iffy whether they could use the trademark, even if they were ok marketing a competing product 2. They don't have the same voice in the technical decisions of the open source project
Moby is an attempt to solve these issues: - It is a project with a vendor neutral name - Presumably, it will be managed in a way that gives vendors somewhat equal footing - It makes it clearer that the pieces are containers, etc, the project that develops all the open-source pieces is moby, and one of the products that integrates all the pieces is docker.
It is similar to how RedHat split out Fedora, except that RedHat didn't see the value in having a RedHat-branded community edition.