[zrail]

You're right that the tooling doesn't support it well but commits have more than one parent all the time, they're just called merge commits.

They can actually have as many parent branches as you please but conflicts get harder to deal with the more parents you have.[1]

[1]: https://www.freblogg.com/git-octopus-merge

[sanderjd]

I realized the multiple parents thing was a total red herring. It really is just the immutability.

What I was thinking of was having multiple parents over time rather than at the same time like a merge commit. But that would just be one (not immutable) parent but with a history of what that parent was over time, not "multiple parents".