> Sure, but since commits have a branch attribute attached to them, "rebasing" does not appear to be "first class".

Again, that's orthogonal: you may or may not use "named branches" (the kind of which persists at commit level), rebasing works either way consistently and predictably.

> It is something that has to be bolted on with an extension.

The extension ships in core, UX is why it's not enabled by default.

> IIUC Git also does not care much about the rebase target being a "branch".

Indeed, it's just that things likely get weird (for no good reason) when you don't (detached head, "unreachable" commits)

> I can live with Git because Git is "enough" if used carefully and after coming to terms with the non-intutive UI.

That's our sad state of affairs. JJ helps a bit, though.