My best-uneducated guess is that it's probably down to the inner circuitry or electrical components of the SCC. Maybe it's the only way the SCC can stop the panels from frying the SCC when the BMS cuts off the battery from the SCC or similar events.That thread talks about short-circuiting the input. Other threads on the Victron Community site say the same thing. What no one has been able (or willing?) to explain is why a controller would ever short-circuit the input. It seems to me that if they want to protect from over-charging, they could just turn off the inputs.
Would love it if someone that perhaps has a deeper understanding of these things would shed some light on this.