You might not think this is that big a deal, but this also means you don’t have to resolve the entire thing in one go. Plenty of times with complicated rebases in git, I’ve not been 100% certain about the path towards resolving it. But jumping around to view various commits when you’re in the rebase-conflict state is painful. In jj you can just switch to an earlier commit, tweak it there, jump to a later commit, see how it looks, etc. It removes 98% of the pain.
It also dovetails nicely with other aspects of jj. Since rebases happen automatically and constantly, they are usually tiny. If there’s a conflict, it’s caught right when you do the thing and not four hours later when that part is no longer fresh in mind. And the op log lets you restore and undo actions atomically, which makes undoing a fuck-up a no-op.