I think rebases are causing so much pain that it is better to have tool support such that they are not needed. E.g. it was a revelation to discover that github doesn't care in PRs - just do a merge with master, done.

As for the working directory - yes, there could be more management around that. I'm not sure why the git community went for nested repos / submodules rather than partial checkouts. It's a different question than the data structure of the repo itself, though. Compared to other VCS it still seems miles ahead.

Large repos: It seems one could alleviate that by limiting the pull history (and LFS if needed), right?