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Comes back to my core values of learn things from first principles.
The command line tool doesn’t change - so it’s a lot easier to write documentation for it and know that the documentation will stay current and won’t be instantly out of date the day a new version of a graphical tool comes out.
If you understand GIT’s command line then it will be easier to understand how deployment scripts work.
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This will give you broader understanding of how GIT can help with many things like deployment.
I can teach long lasting understanding of GIT through the command line and know that I teaching first principles.