The disadvantage is that then you never learn how GIMP works and will forever frustrated it's not Photoshop. Sometimes it's better to take the hard way.
A year or two ago, I ditched doom and rolled my own emacs config, having gained the necessary knowledge and confidence to do so from my years with doom.
Both doom and spacemacs exist to make the (relatively) strange nature of emacs more welcoming to users of other IDEs. I’m not sure I would have stuck with it without them, so I’m not sure the hard way is always better.