Monocock
It's not the switching off that does the damage, it's switching back on while the engine is still turning. The engine will re-start and the unburnt fuel mixture which has been pumped into the exhaust manifold through the cylinders during the period the mags were off will ignite and exlode. This can cause serious damage.
The Chippy is shut down by switching off the mags, but it is done at idle power setting, then the throttle smartly opened to full once the mags are 'off'. The fully open throttle at very low rpm means there is little vacuum in the carb venturi so litttle or no fuel is drawn into the engine (which could cause run-on if there are hot carbon deposits in the cylinders, and in any case would cause oil to be washed of cylinder walls, increasing wear at next startup).
SSD