Because people play Auric for the difficulty and the quickplay goes against it.
Why would you play Hunting Grounds or Hi int zone easy mode when you can play Shock troop gauntlet and get a semblance of real difficulty? When all it takes is a manual choice that is just as easy to make as is the quickplay!
Worse yet, why does it have to be explained?
Here’s a month old thread telling you what happens when HISTG didn’t got updated
TL;DR Auric is Maelstrom and HISTG, the rest is Auric in name only and people it seems vote for that sentiment with targeted queuing instead of going for the quickplay