I think this is cluttering git with a bunch of special-case commands when rebase is all you need. Next thing you know, people will say we need to drop git because there are 5 ways to do everything.
The point is, ergonomics matter. Rebase is not ergonomic for splitting commits.
The point is this is perhaps true for you but most definitely not for others. there’s a Jevon’s paradox-like mechanic at play here which you can’t see if your axiom is ‘I don’t need this.’