Mercurial was safer and better. I still use it and it's still safer.
The bookmarks feature which is supposed to be the solution for short-lived branches is hard to understand though. I'm probably dumb but I can't work it out and hence the overall tool is that much less useful.
It needs a github-like website and Heptapod would be great if I could use it - I've set up a project, been unable to do anything and then had it all closed down. OTOH self-hosting is a lot more feasible nowadays with today's fibre connections.
I hated so much how Mercurial dealt with short-lived branches, that after seeing how Git did it, I've never looked back. I also remember how some people told me to use the quilt or something extension to manage patches, but it was too complicated for me.
It make a lot of sense if you think of repo history as properly immutable, and dispose of the notion that brach is a first class object in the git sense. Bookmakers just pin a checkin hash to a name, and you can have many heads in an hg branch.
What does short lives branches even mean? Make a branch, close it, or merge it.
Short-lived branches are likely referring to "bookmarks" in Mercurial. Or they could also just be un-named anonymous heads. These are different from what is exposed by the "hg branch" command.
Mercurial's "branch" was generally intended for long-lived things. Think the "stable branch" or a "version X" support branch for a project.
The branch name is baked into the commits that use it. You can hide them from the UI with "--close-branch", but they will still exist forever in the commit history. This is both a good thing and a bad thing, depending on your desires.
This is different from Git's "branch" which is basically just a pointer to a commit. It is not part of commit history, it is just a convenience for the developer. Later, Mercurial added "bookmarks" which are similar.