"perfectly good" is a colloquial idiom for "acceptable", "decent", "useable".
Example: "Someone in my building threw out a perfectly good audio amplifier. It just needed a blown fuse replaced inside! I hooked it up to some speakers and now using it for my TV."
It doesn't mean that the hardware is so advanced, it cannot be improved.
Example: "Someone in my building threw out a perfectly good audio amplifier. It just needed a blown fuse replaced inside! I hooked it up to some speakers and now using it for my TV."
It doesn't mean that the hardware is so advanced, it cannot be improved.