So gigabyte has been running back to back competitions with hw and $ as prizes while others do $h1t and yet giga ostracizes its customers.
Additionally, since -as you said- it escapes you, have you thought the following?
a) its bloody 2017 and they don't care about z170 (and they shouldn't). Marketing budget goes on new series of products not old.
b) Might not be the case, but since they want to push z270 imagine if a z170 mobo would win their z270 product series. Not something that they would want to promote imo.