"Just because mini-disc recorders are available does not mean most people have them. Most people have never heard of them"

Even with good mics, live concert recordings from the audience cannot compare to a proper, multitrack recording of a live show. This is not a limitation of the equipment, but the nature of the acoustics, P.A. gear, the inherent crowd noise at a live show, etc, etc ...

There's a lot more to getting a good recording than sticking a microphone in front of the stage. It often takes me 90 minutes or more to unload all my recording gear and get setup for a concert.