"a good system should be able to play all of it (music) well within its power and speaker driver limits". Well of course---"should be" is right! And if one has enough dough, the choice between, say, maximum SPL and amount of bass, versus, for instance, inner detail, micro dynamics, and transparency may not need to be made. There are loudspeakers that DO excel in all those regards, but at what price? Unless I'm mistaken, most of us have to settle for loudspeakers which do NOT excel equally well in all parameters, therefore requiring most to prioritize in the matter of speaker capabilities.
"within its power and speaker driver limits" is a huge qualification! If one doesn't think the music of AC/DC requires a different balance of capabilities than does Chamber Music, so be it; my experience is different. I love AC/DC, but I'm sure not going to play their music on my Quad 57's!---that's what my Eminent Technology LFT-8b's are for. But I find the Quad unequalled for Chamber, Bluegrass, Singer/Songwriter---heck, all acoustic music played at moderate SPL. I listen to J.S. Bach's Concerto for Orchestra and Harpsichord (one, two, three, and four!) and similar music on them, and they allow me to keep all the harpsichords separated, to follow the delicate thread of each as they wind their way through the sound of the orchestra, around and across each other. Very difficult for some loudspeakers to do, loudspeakers which do things the Quads are incapable of doing. Things that AC/DC music requires. Horses for courses, as they say.