> I recall checking Mercurial back in the day and being puzzled by the lack of basic features such as the ability to stash changes. I also recalled that the community was dismissive of the lack of such a basic feature, with comments such as users could always create local branches,

I started with Mercurial, eventually got forced into git, and now use jujutsu.

Totally agree with the Mercurial developers: Just use a branch/bookmark. When I encountered it in git, it seemed neat, but became yet another concept/thing to clean up that you don't need to.

And lo and behold, after switching to jujutsu, everyone shows how you can do a stash using an (anonymous) branch.

Even though I used stash a lot in my git days, I don't miss it at all while using jujutsu. The benefit of jj is the ease with which one makes branches (without needing to name them). That's why you may not have liked the advice in mercurial - it wasn't the solution that was problematic, but that mercurial didn't make it as easy as it should have been.

(Same goes for index - no one misses it once they switch to jujutsu).