[Discussion] Do PVE servers purposely avoid quest items to increase playtime?

I’ve noticed after multiple raids that certain items that are linked to active quests simply do not spawn or spawns so infrequently that I believe it’s done on purpose to increase playtime. Once the quest is done, all of a sudden, the items spawns commonly.

Is this the case or is it simply because the only person looting is yourself + maybe AI? Am I just unlucky?