alt Hacker NewsIt's pretty fast to destroy all the keys in a TPM. Should take a minute if you know the right place to go. Meanwhile securely deleting a normal drive requires overwriting every sector with random data, which could take hours. So it also helps if you're giving away the whole machine.
Smashing the disk with a hammer takes seconds. Or dropping it in a shredder.
Used disks are not worth hours of time to overwrite with random data. Just physically destroy them.