yeah compression allows you to shrink, or perhaps more accurately control the size of that gap between the quietest bits and the loudest bits. why is that useful, well you might have subtle bits of the track that are not audible or insufficiently audible because they’re drowned out by the loudest bits so you want to be able to manipulate that distance so that the quiet bits are subtle but not inaudible and the loud bits are loud but not excessively so relative to everything else.
essentially we’re talking about not drowning stuff out.