That effect of the voices getting quieter when the band gets louder goes back a long way.

With the organs of Bach's time, the blower (human-driven) had limited power, nowhere near enough to sound all the pipes at once. So if you had a steady long note in one part and staccato chords in the others, the long note would have an audible drop in power as each chord sounded, producing subtle articulations that weren't explicitly notated.