Status (active/inactive/other) and existence (present or deleted) are very different things, they may be separated most of the time. Legal requirements can prevent deletion of inactive data, so in some cases one may have a lot of inactive but must keep data. Soft delete can help in some scenarios, for example you want to give people a way to re-activate accounts, but hide the ones marked as deleted.
All this essentially forces the use of some sort of soft deletion. (Activation flags are sort of just a more complicated form of soft deletion).