Fair enough, but I suspect in this case it's your previous experiences with VCS that make it take more than a few hours. JJ is actually simpler than git. There is no staging, no committing, less need for rebase, undo just works, it has better history - lots of things. The need to learn all those git concepts disappears with JJ. For a new user that makes life easier. But someone who comes from git has to unlearn a lot of things before they can adjust to the JJ mindset.
If all you ever do in git is "git pull; git add -A; git commit -a -m ...; git push", then switching to JJ is hard justify. Dropping the need to type "git add -A; git commit -a -m ..." isn't a big win. That's all most people do, so I expect most won't change.
But there is a reason that's all most people do in git - it's because everything else is far more messy, and dangerous. If you haven't lost work to "git reset --hard", you haven't been using git for long. Once you notice it easy to do more in JJ, things like breaking up big PR's in a series of commits that spell out a narrative of how you got from A to B, which eases the burden on the reviewer, become downright easy. Shuffling code between commits to achieve that in git is a right proper PITA, so JJ users tend to have a much tidier commit history.
That change only happens when you've become so familiar with JJ concepts, you are no longer "thinking in git", so much so the shift back to git's CLI becomes painful. It takes months. Until you get that payback, the switch is wasted time.