One benefit of uploading things immediately is that you can launch a research job, run CI, or share code between all of your developer environments absolutely trivially. The commit hash "just works everywhere". There is a major benefit here and Scion does have some extra features not listed in this blog post, such as the ability to bundle these commits into useful, shareable workspaces that track the heads dynamically.

Sure, I'm not saying that I don't like the ability to very quickly do a push to some remote and potentially temporary spot. I just also want the ability to not do this without loss of functionality.