Modern setups are being designed to act like turbos... but the fact remains they are rpm based.
You could say the same about turbo's....their goal is to make boost. Other than that, I don't understand what you mean "designed to act like turbo's"
As far as "RPM based", I think i know where you were going with that, and yes, obviously the faster the engine turns, the faster the SC will turn. However, they are not always putting boost into the engine.