You can delete 1 post at a time. you can export a range of posts based on dates. it would be nice if you could delete posts between dates.
For example if you want to archive your posts between a set date so as to save space, basically not see them on screen, but know that you can easily get to them when required.
Now on deleting, you might want to delete posts that you have already exported but you don't want to do that 1 at a time, but want to specify a date range to delete.
Is that ok explanation for you?