I hear what you are saying but by the time you add those extra switches and midi controllers ets you have a board that is as big a as Stage but less integrated and with less I/O options and less expression pedal options. I don’t see the attraction of a pieced together board over an all in one.
While true that once you start integrating into a pedalboard you are now the size of a Stage but you can add things that Kemper does not offer.
For my use I’ve add a guitar synth, wah, expression for synth, extra drive pedal, Pederson tuner with options for alt tunings
My KPP has a display thanks to Retrovision and I use a power brick under my board, so no wallwart plug just a simple IEC to power everything.
So it really comes down to how you want to use your Kemper product. Choices, choices.
I also have a Rack as well but have been using the KPP exclusively for live.