This is a little hyperbolic though, because git does have UI above the reflog designed for catching the most common mistakes. The reflog is a powertool, it is not the default UI, and most people never need to look at the reflog.
git rebase has an "abort" feature when you need to redo it. git has tag & branch & stash features if you want to save what you're doing before you rebase. The problem with keeping and showing rebased branches are that 1- you don't need them after the rebase is successful. You only need them when the rebase is going badly, and 2- you'd have a lot of unnecessary noise pile up. I often rebase multiple times before every push. I don't want to see them all, you probably don't either.
That said, I fully agree that git's UI could be better and help beginners feel less fear!
A good UI should allow you to recover from mistakes. Like the trashcan vs rm example everyone is using.
It's good that git doesn't permanently delete stuff, it's bad that you need to be a relative expert to know that. If git branch showed rebased branches and told you they would disappear in x days then beginners might feel less fear and embrace the power of git faster.