bowlofspinach says:
...the main thing being an additional GM is good for is to take over when the main GM leaves.
This makes me ask the question "Why do people want to have a secondary GM in the first place? What's their purpose?"
My assumption was that it would be good for games where you have a mentor/mentee thing going on (haven't seen one of those pop up in a while, but I remember them). Or you have a GM that wants to take a break and let a player take over for a little while, so they bring them up to Secondary GM level so they can run a game for a bit while still staying within the game's forums.
Is there a use case that I'm missing that requires the use of a secondary GM? Rather, are there use cases without simple workarounds that would work better than all this permissions hullabaloo?