People usually shut down profiles for privacy reasons, so deactivation will rarely be of any use to them; they are better off trying to manually delete their content, while they still have a semblance of write access in that regard.
Deactivation works in some instances on a hypothetical level, but people tend to leave a service, because they don't trust it, which leaves that option moot.
Deletion erases data.
People usually shut down profiles for privacy reasons, so deactivation will rarely be of any use to them; they are better off trying to manually delete their content, while they still have a semblance of write access in that regard.
Deactivation works in some instances on a hypothetical level, but people tend to leave a service, because they don't trust it, which leaves that option moot.