The low-pass is the most musical filter there is: close it and a bright sound ducks underwater, open it and the track blooms back. Decades of dance music builds ride exactly that gesture.
Technically it attenuates above its cutoff frequency at some slope, with resonance emphasizing the edge. In analysis rather than sound design, low-passing a control signal is smoothing: an envelope follower is essentially a rectifier and a low-pass filter in a trench coat.
Reactive visuals use both senses at once. Filtering the audio isolates the band you care about; filtering the resulting control signal decides whether the motion jitters or glides.