Someone quoted a study the other day, I can’t find it right now. The gist of it was that the function performed very poorly and was just not what you would consider a ‘secure’ erase, i.e. it was possible to restore a lot of data still. This raised a security concern and Apple’s formal solution was removing it altogether. Apple also says that it is counterproductive on SSDs due to their technical nature, as (1) the OS doesn’t control what the SSD’s micro-controller does when it is instructed to ‘overwrite’ the data and (2) that an SSD never actually overwrites but deletes data once a page is marked as stale. All in all, if you need this function for security reasons, you’re better advised to use disk encryption and a firmware password.
