mobGriefing and Mobs picking up Items

I turned MobGriefing to false so i couldn't get blown up by creepers and was about to equip skeletons with swords and use them as guardians for my castle

What I expected to happen was, that "mobGriefing false" would only turn off actual griefing like Creeper explosions and Enderman destroying the environment.

What actually happened was that no mob could pick up any item. Skeletons and Zombies are affected by this.

Steps to Reproduce:
1. Play on hard
2. turn mobGriefing to false via /gamerule mobGriefing false
3. spawn multible zombies or skeletons with a spawn egg
4. throw a sword or a piece of armor into them

Note:
Even if this was intended, it shouldn't be. It would make sense, if they destroyed the items, but if you kill monsters that picked up any item, said item will be recovered 100%. This is not griefing but simply a feature.