Because the lack of downward mobility suggests the same problem as the upward mobility: your success in life is based on your parents income not your own merits.
If you want a meritocracy you have to accept that untalented/unmotivated kids of rich parents may become relatively poor.
Well if you really want to optimize for social churn, couldn't you just randomize all the newborn babies at hospitals or something?
Re:The American Dream Is Alive in Finland
by drjesusphd on Tuesday July 12, 2016 @02:42AM
(#12077172)
This has nothing to do with genetics.
Which makes me wonder why one would laud upward mobility in percentiles, when any such upward mobility must be balanced out by equal and opposite downward mobility.