What am I missing?
The requirement appears to add nothing to the (general) requirement to run a ground wire / EGC with all feeders- and your grounds are required to be connected at transfer switches, transformers, etc. as well.
I could see this requirement as making sense if you had planned on using the conduit as your ground. As I see it, though, you're going to be running an EGC a lot larger than #10 anyway.
