Isn't that just svn? Why force a git-shaped peg into an svn-shaped hole?
Admittedly, 99% of people are using git as a centralised source control system, and outside of branching/merging there hasn't been much of a change in workflow for many. I've not used their system, so I don't know how well this svn-like system works, but every time I think back to svn all I can think of is how painful this workflow was.
You can also create a worktree for a quick experiment (eg how many conflicts when I merge X and Y) and just rm it when you're done.
Sure, all these things can be achieved with git stash and git reset... but they are both difficult to keep track of and will cause your IDE to run its expensive reindexing.
It's kind of like how you could use pushd/popd and open subshells to work in one shell, but people prefer to just open another terminal window.