Rebooting just seems like a very roundabout, slow and inefficient way to get back to that initial state you describe.
It’s exactly what the reboot process is designed to do; return you to that fully encrypted pre-boot state. There would be no purpose to implementing a second method that does the exact same thing.
WhyJiffie@sh.itjust.works 3 hours ago
its done that way because at a reboot all memory is lost, and it can’t happen that something slips through because there is a bug or some miscalculation