One way I compare the git to jj transition (if it happens, or for whom it happens) to the svn to git transition is: branching in svn was awful. It was heavyweight and you were signing up for pain later down the road. Git made branching easy and normal, almost something you barely need to think about. jj does a similar thing for rebasing. For someone whose familiarity with git is clone, pull, push, merge, creating branches (so, basic/working/practical familiarity but even "rebase -i" might be pushing the limits)- for someone like that what jj offers is a similar "lift" of a feature (rebase) from "scary" to "normal" similar to what git did for branching compared to svn.

That's just one aspect of the whole thing, and of course if you're a git rebase wizard (or have tools that make you that) then this won't seem relevant. But I think for a lot of people this might be a salient point.