WoW is wishy-washy about it. Sometimes we can share, sometimes not.
If I didn’t know any better, I’d swear we were in the middle of a social experiment. They give us more of the “shared” items, so that we can realize how stupid it is when we DON’T share items.
I think the only thing in Legion we didn’t share was mobs under the Sentinax. And as soon as farming shards under the Sentinax became a thing (6 hours after it was released?), the boards were FLOODED with people complaining about how stupid it was that we didn’t share taps.
And as someone that’s been outspoken about removing Factions since WoD, I see that as a wedge into the system. It helps people realize just how stupid and pointless it is. So we get just enough things that we can’t share… so people realize things like that don’t help the game.