What is mortality rate in dragon ball and why they considered destroying universes for that?


I'm not able to understand what is the meaning of mortality rate as referred
in episode 84 when it is said that universe 7 has low mortality rate so what
they meant with that and why they considered destroying universes for that.




As quoted in Pablo's [answer](https://anime.stackexchange.com/a/47527), the
Mortal Level is a measurement of the quality of the mortals used by the Kings
of All. We're not really told exactly what goes into deciding this value,
other than a singular data point from the manga (which did not happen in the
anime, however, to my recollection):

> In the manga Universe 7 gets enough of a score boost to rank-up (a single
> position) thanks to 17's wish to bring back all of the destroyed universes.
> So setting aside selfish desires to save things beyond yourself that
> normally would never affect you is apparently one of the dimensions for
> evaluation.

We're also not explicitly told _why_ this measure was developed, etc. But the
implications are clear: the universes were created _for a purpose_ , and that
purpose is not simply to exist and unfold in whatever way they desire. The
creator god(s) are not simply watchmakers and observers, but are actively
engaged in their creation for whatever that purpose is. That purpose is
evidently measured, at least in part, by Mortal Level. Universes which
systematically fail to live up to that purpose are subject to destruction.
Perhaps the Kings of All had a motive similar to the creator gods in the
Tenchi series: to see if they were powerful enough to create something more
powerful than themselves. If so, maybe that's why Whis was always hoping Goku
and/or Vegeta could achieve Ultra Instinct. Perhaps they just wanted
companions and entertainment the angels couldn't provide, and created
universes so that they might produce such beings, and universes that seem
incapable of doing so can be discarded. Perhaps it is all just a form of
entertainment, as we have at times seen the Kings of All acting bored and
wanting something interesting to happen. In which case the Mortal Level might
just be an arbitrary measuring stick created simply to give a sense of
challenge and excitement: see how high the universes can go, see what you can
do to get a higher score, but with no purpose _beyond_ the score. Universes
that do poorly could then be discarded, like one might delete or reset a video
game save that doesn't go as well as one desired. Got caught pickpocketing in
Skyrim? Reload and try again!

One way or another the Kings of All are meant to be alien: their values and
goals are fundamentally different from our own, or from (most of) those
inhabiting the universes.

