That's the point, isn't it? According to mormons, that makes it justifiable for the "temple work" of baptism of millions who passed on without being exposed to the "restored gospel" of Joseph Smith.
Of course, no one, including the descendants of many of these dead, has given permission for these rituals to be performed, and many are insulted at the liberties taken in doing this.
True, and some might be insulted if a priest were to give last rights to a member of their family without their permission/request.
Jewish people have been particularly insulted in the last few years, because the Mormon Church obtained name lists of many of the murdered Holocaust Jews and starting calling their names out in their ritual baptisms for the dead. The Jewish surviving families said they'd suffered enough from Gentile religions and didn't want their family names to be used in Mormon temples.