Because for me the mixer is part of my instrument, and I want to record exactly the same mix as on the main LR out but split into separate tracks for easier editing and post processing.
This includes EQ, mute and fader.
Pre-everything direct outs are already available on the channel inserts.
The schematics for the mixer is available on the net. I simply tapped the audio where it enters the pan pots. I used two 470 ohm resistors to hot and between GND and cold (impedance balanced). Could use lower values but had a bunch of these.. Made a PCB with an IDC connector, resistors, and the DB-25 connector. Happy to share the gerbers if anyone interested.