Sure, you could view it as Drobox's problem, but the core of it is that git relies on things that Dropbox doesn't support, while jj does not. And so it's usable more safely in more contexts.
I fully agree that this is a niche use-case.
I fully agree that this is a niche use-case.
This wasn't what I was talking about, I meant that you should create a bare repo and push to it, not that you work directly in a directory in Dropbox.