Be able to use filter (highpass\lowpass) inside Send section. Useful when you ned to highpass bass guitar before hitting AUX bus which contains Reverb plugin. If this Reverb AUX receives audio from multiple other channels (Mix Room Track) you can`t highpass bass guitar by placing filter in AUX input slot, because you will highpass whole thing. And you can`t highpass Bass placing filter on original track, obviously. You need to highpass only send from bass guitar track. So, you need filter INSIDE Send section. For each send.