I do think hosting is an important part of the VCS story. I agree that hg and jj and sapling are capable of being front ends to a google3 like backend GitHub like thing to support it (Google has this internally for jj). Of course some people are working on hosting solutions for these but it feels wrong to me that hosting platforms and their underlying VCS are not made by the same team. IMO people like google3 so much because it’s one integrated system which is the approach I’m trying with Oak.

Public hg and jj are just a front-end to git. No virtual file system overlay or anything like that. Meta has open sourced many of the components of sapling, but there is no plumbing to put it all together in the same configuration.