As the title states, if the only changes one is making to the GP theme are CSS, via your Simple CSS plugin, does one really need a child theme? In other words, are you CSS changes maintained when the GP theme is updated?
On a side not, I noticed while making some CSS adjustments, that the Simple CSS plugin editor and the one that shows up in the Customizer aren’t always in synch. Should they be? I removed some lines in the Simple CSS plugin editor screen (like that one better as there is more real estate for these tired old eyes) and save, but then wondered why the changes weren’t being reflected on the site. Went into the Customizer Simple CSS editor, and those removed lines were still there.
Cheers!
Lyle