From my small company experience, this is more likely incompetence than maliciousness. Spreadsheets get passed around and remerged back into the blob. Mind you,

From my small company experience, this is more likely incompetence than maliciousness. Spreadsheets get passed around and remerged back into the blob. Mind you, I don't mean to excuse this behavior. Just to understand it. And of course, unsubscribe processes will be near the bottom of anyone's priority list until the complaints and threats begin to mount.