I think we are getting confused on terms here:
Idol summons like monks and siege archers, as well as unique summons like Yetis and Spirits, provide neither gold nor xp when killed.
Portal grunts like minotaurs, archers, priests, angels, and catapultasaurs provide both xp and gold when killed.
Minions vs Grunts/Creeps/Reinforcements : No XP/Gold vs XP/Gold