There is no need to seperate earth terminals on a Domestic install. You are right Stuey in what you say but lets not take things to the extreme.
This sounds like regurgitated carp from some college lecturer.
Switching PSUs are a slight problem we are all aware DC equipment has a higher earth leakage but how many does the average house have ?
Do you know how this installation is used by looking at a picture ? This install could be a elderly couple house, not a hackers house with multiple USB sockets and PSUs plugged in.
Led lighting is not usually applicable to either as this on the lighting circuit.
Lets not jump in and insult someones work, leave all this rubbish to the Facebook groups