After reading the article, it still was not clear to me why I would need this over git, Github, and a bunch of branches/worktrees.

On further analysis, it seems that the argument is "it's expensive and rate-limited to create thousands of repos/branches on Github" and "We built ArtifactFS as a lazy filesystem that hydrates files on-read, for big repos."

So if those fit your usecases seems like a nice tool, but I'm imagining the market is niche here.