If you expect that you can complete some task just from the keyboard, then the idea of having to use the mouse interrupts what you're doing.
The original post gives "stage and commit in git" as an example. Magit is much nicer than CLI, since you can quickly invoke the actions you want; it's less effort than typing out the full command on the CLI. -- With LLM coding agents, getting an LLM agent to make a commit is slower than doing it yourself in magit (if all you're going to do is stage and commit), but it's much less effort.