I used to use it like that but it was too much work to manage multiple repositories in such way especially if i didn't remember all changes I made.
Using Fork greatly reduced time spent making useful commit messages by having all changes visible at glance. It even allows to stage specific lines of source code and has insanely good interactive rebase UX.
Things like that are impossible to achieve with only using cli productively.
Also I like the ability to see commits from all branches at glance.