“The smartlog is one of the most important Sapling commands and the centerpiece of the entire user experience.”
Meta spent ten years scaling Mercurial for a monorepo with tens of millions of files and commits, and this is what came out. The client works against Git repos today. The server that makes it scale is still mostly internal. Git’s UX really is bad, so the client alone might find users. Just don’t expect Meta’s repo performance without Meta’s backend.