It was as if the Metal Ogres knew that they had enough manpower (or Ogrepower) in their possession that their leaders had decided that this extraordinary odour of their prey was worthy of a huge feast. That monster lure was basically a trigger to force them out of their own personal habitats within the dungeon and emerge hungry.
They had no idea what made them so compulsive to get this extravagant sensation out of their body other than to gather and hunt as a group. (Well, to break the bubble, it was the Synthesis AI Administration that created all of this and programmed their behaviour in such a way.) While he did not precisely question Syn, Jin fully knew well that the AI administration had a hand in this situation but in his honest opinion, they did not need to create a brand new variant to see how effective his incoming customers would be.