That said, low impedances look like constant voltage sources or shorts, and carry a lot of current, while high impedances look like constant current sources or opens, and develop a lot of voltage. It's plenty of an approximation, but when you call an SWR < 1.2 a good match, it doesn't take much in either direction to produce that.
This is relative to system impedance (50 ohms, say), or if not in a system with characteristic impedances, then some factor of Zo (377 ohms). At "lumped constant" frequencies, Zo and SWR and stuff aren't all that relevant anymore, but the concepts always apply.
Tim