Last I knew, the FB mainline codebase was in fact still in SVN with git-svn dcommit (possibly hidden under arc) being how things land in "master" (and the revisions being merged quasi-manually to a release branch immediately before HH compile)

FB doesn't need to branch ... Gatekeeper (their A/B, feature flag system) really takes care of that concern logically

There's a big difference between a linear history produced by actual linear development and one produced by `git rebase -i`. They both have the advantage of being easier to understand later, however.

That's not true dude. If you're following actual linear development you're likely to see a lot of 'poke build' and 'change css' and stuff like that. Git rebase -i gives you a change to rename your commit and organize it in a readable way.

So git rebase -i will be more readable, while actual linear history is always gibberish.