Its about "break points", for example for spica to 1shot those flying eyesballs at the hard mode on thursday dailies you need her to be level 61-ish. If you skip 10 stats, will she still be able hit the "break point" to 1 shot those eyeballs?
Some units also have abilities that buff the stat given, eg. 2.3x the def = 10 pointx2.3 = 23 def loss during the important activation time against a boss.
Also when you watch videos displaying your units on how to clear harder maps, you must now take into account the loss stats, which will bother you ...forever.