So basically it's a branch?
It's visible in code review UI, has a description, has tests run on it, it can be merged by other people and it can be referenced from anywhere. Eventually it's merged into the head or dropped.
If every branch was always merged back into head before doing anything else, and always had its commits flattened into one, and someone forking off of your branch was basically opening it up, copying the changes in your clipboard, and pasting it into a new branch with no attribution or history, then sure.
With branches, if someone updates the branch you depend on, your work is based on stale stuff, and it can get ugly. Just try to do it on github :-)