Did they give an exact date for this feature to be implemented? I recall that they hyped the feature as coming soon but I don't recall if they gave a deadline for it being in the users' hands. Not trying to make excuses for them, but to be fair you need to show us where they promised it at a particular date or with a specific software release/update. I still recall that being a "we're working on it/coming soon" sort of thing but I could be wrong.
I wouldn't fault Apple for problems with their suppliers. We're talking about situations where Apple promised something and they were directly responsible, as part of some apparent history of over-promising/under-delivering, for the failure to meet said promise. Failure by a third-party doesn't really reflect on Apple's character as a company.
Meh... maybe. If a company hypes features as super secret, it has to be something bigger than stacks. I'd half-way count that against them. Stacks is cool but not a hype-able feature.
Okay. Got me there.