Transient was factored out much later. It's not just transient that makes magit great, though. It's the only alternative porcelain for git that I'm aware of and one that makes git both easier to use and understand. I'm the "git guy" at every place I've worked but I owe it all to magit. Other git frontends just do the CLI stuff with point and click, they don't help you understand what's going on at all.
